si Si i! ru r^- =o LT) _D CD o D m AN ACCOUNT OF THE CRUSTACEA NORWAY WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES BY G. O. SARS VOL. VI COPEPODA CYCLOPOIDA PARTS I & II OITHONID^E, CYCLOPINID^E, CYCLOPIDjE (part). WITH 16 AUTOTYPIC PLATES BERGEN PUBLISHED BY THE BERGEN MUSEUM ( SOLD BY ALB. CAMMERMEYEE'S FOELAQ, CHRISTIANIA 1913 INTRODUCTION. Under the head Cydopoida I comprise a number of Copepoda, which on the whole may be said to be built upon the type of our common fresh-water fleas (Cyclops), though exhibiting many modifications, both as to their general ap- pearance and to their habits, the latter affecting chiefly the structure of the oral parts. The present group, or sub-order, exhibits some relations both to the Calanoida and to the Harpacticoida, and also shows a certain approach to some of the other sub-orders distinguished by the present author, especially to the Notodelphyoida and the Caligoida, though the Cyclopoid type may always be easily recognisable. Whereas the extensive group Harpacticoida by earlier authors has generally been comprised within a single family, the Harpacticidce, several families referable to the present sub-order were established very early, though their real connexion under a common type has not been recognised. According to the system proposed by Dr. Giesbrecht, the Cydopoida, like the Harpacticoida, should be included in the 2nd of his 2 primary divisions, the so-called Podoplea. This very extensive and heterogeneous group has been divided by that author into 2 sections, Isokerandria and Ampliartlwandria, according to the non-prehensile or prehensile character of the anterior antennae in the male, each section comprising several families, which have been enumerated in his recent work on the family Aster oclieridce, p. 57. I am, however, by no means prepared to adopt this classification, which appears to me quite artificial, like the primary grouping of the Copepoda into Oymnoplea and Podoplea. In the sense here adopted, the sub-order Cydopoida comprises families referred by Dr. Giesbrecht partly to the Isokerandria and partly to the Ampliartlwandria, whereas other families included by that author in the latter section are wholly removed as types of distinct sub-orders. One of these, the Harpacticoida, has been treated of in the preceding volume, the 4 remaining sub-orders, Notodelphyoida, Monstril- loida, Caligoida and Lernceoida, being reserved for the succeeding volumes of the present work. 1 Crustacea. As mentioned above, the habits of the Cyclopoida are much more varied than is the case with the Calanoida and Harpaeticoida. Some of them, for instance the species of the genus Oithona, are true pelagic animals, constituting a chief part of the plankton in almost all regions of the Oceans. Several other forms, like the Harpaeticoida^ live near the shores among algse or on a muddy bottom at different depths, and a great number of forms lead a more or less pronounced parasitic existence, attacking different invertebrate animals, in some instances also fishes. In most cases, however, the parasitism may be said to be merely temporary, though there are also a few examples of a more permanent parasitism, for instance in the case of Eryasilus and Nicothoe. The different mode and degree of parasitism has a great influence on the structure of the oral parts, and indeed we have in this feature a good guide for an exact subdivision of this group of Copepoda. The parasitic forms exhibit, as regards the structure of the oral parts, 2 well-marked types, both again differing conspicuously from the non- parasitic forms. We may accordingly divide the Cyclopoida into 3 natural sec- tions, for which I propose to retain the well-known names: gnathostoma, siphono- stoma and poecilostoma. These names were first proposed by Thorell, but were taken in a much wider sense, viz., to divide the entire order Copepoda. I here restrict them to the group of Copepoda which will be treated of in the present volume. As to the general characters distinguishing this group, the external appearance of the body, as a rule, looks rather different from that found in the typical Harpaeticoida by the very sharp demarcation of the 2 chief divisions of the body, the anterior one being more or less tumefied, the posterior very narrow. So far the Cyclopoida more resemble the Calanoida than the Harpaeticoida, though they are easily distinguished from them by the very moveable articulation between the last 2 trunk-segments, the posterior of which, as a rule, is very small and firmly connected with the genital segment, so that, at first sight, it has the appearance of belonging more properly to the posterior than to the anterior division of the body. The anterior antennae are, as a rule, more elongated than in the Har- paeticoida and are composed of a greater number of articulations. There are, however, also some instances of a more or less great reduction of these limbs, both in size and in the number of joints. The posterior antenna are generally simple, without any outer ramus or exopodite. Only in a few of the parasitic forms is there a slight rudiment of such a ramus. In several of the poecilostomous Cyclopoida these antennae are transformed into powerful prehensile organs. The oral parts, as mentioned above, are of very different structure in the 3 sections of Cyclopoida. The natatory legs are, as a rule, shorter and stouter than in the Har- pacticoida, with the basal part broad and flattened and the rami generally well developed and subequal in size. The 1st pair are smaller than the succeeding ones and never prehensile. In a few of the parasitic forms, for instance Canceritta, a considerable reduction of the natatory legs is found to have taken place, at least in the female. The last pair of legs are always very small and simple in structure, being in most cases exactly alike in the two sexes. The ova are carried in 2 ovisacs, which are lateral or even subdorsal, never, as in the Harpacticoida, ventral. Only in one instance, viz., in our in- digenous species of Corycceus, have I found only a single ovisac, which, however, is attached quite dorsally. The Cyclopoida are well represented also in fresh water by numerous species of the genus Cyclops and allied forms, and some of the parasitic forms, for instance Ergasilus, are also true fresh-water animals. Section 1 Gnathostoma. General Characters. Anterior antennse in male distinctly hinged. Posterior antennae without any outer ramus, and carrying on the tip a number of curved setse. Oral parts adapted for mastication. Masticatory parts of mandibles and maxillae strongly dentate. Maxillipeds not subchelate; the posterior ones smaller than the anterior, and of the same appearance in the two sexes. Natatory legs well developed, with both rami generally 3-articulate. Remarks. The several forms belonging to this section have generally been combined within a single family, the Cydopidce. It is, however, very easy to distinguish at least 3 well-defined families of gnathostomous Cyclopoida. All these 3 families are represented in the fauna of Norway, and will be shortly characterised below. Fam. 1 . Oithonidae. Characters. Body slender and of a very delicate structure, with thin and pellucid integuments. Anterior antennae in female very slender and provided with long diverging setae; those in male much more robust and distinctly geni- culate. Posterior antennae comparatively small, with the number of joints reduced. Oral parts well developed, and rather different in structure from those in other Cyclopoida, being partly armed with claw-like spines. Natatory legs with com- paratively slender 3-articulate rarni edged with unusually long setae. Last pair of legs rudimentary and partly confluent with the corresponding segment. Caudal rami differing in shape and armature in the two sexes. Remarks. This family is founded upon the genus Oiihona Baird, which in several respects differs rather conspicuously from the other genera included in the present section, and may accordingly be entitled to constitute the type of a distinct group. We do not know as yet any other genus referable to this family. The genus Mormonilla of Giesbrecht, it is true, exhibits some resemblance to Oithona in the general appearance of the body as also in the structure of the anterior antennae; but the posterior antennae are very different and built wholly on the type of the Calanoida. The systematic position of this genus is still very doubtful, though it perhaps may be found to be nearest related to the Cyclopoida. In this case it must be regarded as the type of a very anomalous family of the gnathostomous Cyclopoida. Gen. 1. OlthOna, Baird, 1843. Syn : Scribella, Dana. Generic Characters. Body slender and attenuated, with the anterior division only slightly dilated, the posterior very narrow, linear in form. Head defined from the 1st pedigerous segment by a well-marked suture, and generally produced in front to a sharply-pointed rostrum, wanting, however, in male. Anterior antennae long and slender, scarcely tapered distally, and composed of a limited number of joints, some of which are imperfectly defined. Posterior an- tennae abruptly bent in the middle, and apparently only consisting of 2 joints, the 1st carrying about in the middle behind a short seta arising from a knob- like prominence. Mandibular palp with the basal part greatly produced, pediform, terminating in 2 claw-like spines, inner ramus represented by a very small seti- ferous appendage attached outside the basal part at some distance from its end, outer ramus well developed and abruptly reflexed, being composed of 3 4 joints carrying long plumose setse. Maxillae with the masticatory lobe well defined and carrying a number of sharp claw-like spines accompanied inside by a thick seti- form appendage, palp lamellar, with the outer distal lobe very small, proximal lobe well developed, recurved, and provided at the tip with long plumose setse 1 ). Both pairs of maxillipecls slender and elongated, the anterior ones 5-articuiate, the posterior ones 4-articulate, both carrying long anteriorly-curving spines. Na- tatory legs with no distinctly developed seta inside the 1st joint of the outer ramus, apical spine of this ramus very slender and serrate outside, spines of outer edge more perfectly developed in male than in female. Last pair of legs represented by a small conical joint terminating in a long seta; another similar seta issuing from a knob-like prominence on each side of the segment itself, seems to answer to that arising from the basal joint of these legs in other Cyclo- poida. Caudal rami in female strongly divergent, with the 2 middle apical setse much elongated and crossing each other at the base; those in male of quite normal appearance. Remarks. The present genus was established in the year 1843 by Baird, to include a species, 0. plumifera, taken in the tropical part of the Atlantic. Another genus with the same name has been established by Alder and Hancock for a nudibranchiate Mollusc; but as this genus is of younger date than that of Baird, its name must be changed. The genus Scribella of Dana is identical with that of Baird, and likewise of later date. Several species of this genus have in recent times been described from different parts of the Oceans. Thus Dr. Giesbrecht records no less than 8 species, and some additional species have been named by other authors. There is, however, still considerable confusion about the right identification of some of these species, partly owing to their close relation and partly to the difficulty which is connected with an exact ana- tomical examination of such delicate and fragile animals. One of the species described by Dr. Giesbrecht, 0. nana, seems in some respects to differ more conspicuously from the others, and may perhaps be regarded as the type of a separate, though nearly allied genus, for which the name Oithonina may be proposed. To the fauna of Norway belong 2 well-defined species, to be de- scribed below. 1 ) I have formerly described these 2 lobes as the exopodal and epipodal lobes, but find that these names cannot properly be retained, since they unquestionably, as is clearly seen in the present genus, answer to the inner and outer rami of the mandibular palp. As, however, both these lobes are always attached outside the palp, I find it more appropriate to give them the indifferent names of proximal and distal outer lobes. 1. Oithona spinirostris, Glaus. (PI. i & ii). Oithona spinirostris, Glaus, Die freilebenden Copepoden, p. 105, PI. XI, figs. 4 9. Syn: Oithona challengeri, Thompson. plumifera, Scott, (not Baird). atlantica, Fai-ran. Specific Characters. Female. Body exceedingly slender, with the anterior division narrow fusiform in shape, the greatest width scarcely exceeding Vs of the length and occurring somewhat in front of the middle. No conspicuous plumes present laterally. Rostrum strong, spiniform, and only very slightly curved, so as to be visible in the dorsal aspect of the animal. Tail not much shorter than the anterior division and very narrow ; genital segment about the length of the 2 succeeding segments combined, and conspicuously dilated in its anterior part. Caudal rami nearly as long as the anal segment and rather divergent, seta of outer edge attached close to the base, the 2 middle apical setse almost twice the length of the tail. Eye narrow linear in form and of a deep red colour. Anterior antennae very slender and elongated, reaching, when reflexed, to the end of the 2nd caudal segment, and composed of about 12 more or less distinctly defined joints of rather unequal length and carrying scattered exceedingly long setse pointing in different directions. 1st pair of natatory legs with the inner ramus distinctly 3-articulate, all joints of outer ramus spiniferous outside. 2nd and 3rd pair with no spine outside the middle joint of the outer ramus, terminal joint of this ramus, as in the 1st pair, with 2 spines outside. 4th pair with no spines outside the first 2 joints of the outer ramus and with only a single setiform spine outside the terminal joint. Ovisacs narrow oblong in form and greatly divergent, in some cases extending nearly at right angles to the axis of the body, each sac containing only a limited number of very pellucid ova, generally arranged in a double row. Male much smaller than female and of a rather different appearance, the body being comparatively less slender, with the front obtusely truncate and wanting any trace of a rostrum. Tail distinctly 5-articulate, with the 1st or genital segment greatly swollen, to receive the 2 spermatophores. Caudal rami shorter than the anal segment and not at all divergent, apical setse much shorter than in female and of quite normal appearance. Anterior antennse scarcely longer than the anterior division of the body and exhibiting the usual geniculation ; middle section only slightly tumefied, terminal one biarticulate. Natatory legs with all the joints of the outer ramus spiniferous outside, 3 such spines being present on the terminal joint in the 2nd and 3rd pairs. Setse of last pair of legs much sherter than in female. Body in both sexes highly pellucid and nearly colourless, though in adult females generally a light orange pigment is seen clothing the oral area and partly also the sides of the head. A large oil-bubble is often found within the posterior part of the trunk, and 2 smaller ones at the limit between the head and the 1st pedigerous segment. Length of adult female 1.35 mm., of male 0.82 mm. Remarks. I regard it as beyond all doubt that the above-described form is that originally recorded by Glaus under the name Oithona spinirostris. It has generally been confounded with the very nearly allied species described by Baird as 0. plumifera, from which, however, it is at once distinguished by the absence of the very conspicuous brightly-coloured plumes projecting in the latter at each side of the trunk, and from which indeed the specific name plumifera has been derived. These plumes in reality belong to the natatory legs, and are formed by the setse attached outside the 2nd basal joint of the legs, which in the said species are richly plumose, whereas in the form here under consideration they ars simple and do not even project laterally. In addition to this distinguishing character, Mr. Farran has recently pointed out some minute differences in the structure of the oral parts between these two forms, which accordingly must be regarded as distinct, though closely-allied species. Mr. Farran has proposed a new specific name for the present species, viz., atlantica, but I think that his doubt about the identity of Glaus' species with the one here under question cannot properly be approved. Occurrence. I have observed this form in many different places on the Norwegian coast, at least up to the Trondhjem Fjord. It is, however, not nearly so common as the next species, and seems more properly to be an inhabitant of the open sea, from which it is only occasionally brought in by the currents to the shores and fjords. When kept living in a vessel with fresh sea-water, the specimens are always found freely suspended in the water, more generally in an erect attitude, with the anterior antennae and the caudal setse spread to each side, these parts apparently serving as a very effective balancing apparatus. In this attitude the animal often rests for long time nearly immobile, only now and then, by the action of the natatory legs, making a short bound to change its place. To judge from the structure of the oral parts, the animal must be of a very rapacious nature, probably feeding upon other small pelagic animals. These may at first be seized by the slender maxillipeds and by them thrown in against the 8 other oral parts, the structure of which indeed seems to be more adapted for killing than for masticating the prey. Distribution. As this form has generally been confounded with 0. plumi- fera, its true distribution is as yet rather difficult to determine. In all probability it has a similar wide range in the Oceans to that of the next species. With full certainty it may be said to be distributed all over the North Atlantic, as also in the Mediterranean. 2. Oithona helgolandica, Glaus. (PL III). Oithona helgolandica, Claus, Die freilebenden Copepoden, p. 105, PI. XI, figs. 10 12. Syn : Oithona spinifrons, Boeck. pygmcea, Boeck. similis, Claus. spinirostris, Giesbrecht (not Claus). Specific Characters. Female. Body of the usual slender form, though somewhat less so than in the preceding species. Rostrum, as in that species, acutely pointed, but abruptly bent downwards at a right angle to the axis of the body, so as not to be visible in the dorsal aspect of the animal. Genital segment somewhat less dilated in its anterior part. Caudal rami not nearly attaining the length of the anal segment, and less divergent than in 0. spinirostris, seta of outer edge shorter. Anterior antennae, when reflexed, extending scarcely beyond the anterior division of the body, and composed of about 10 joints, some of which, however, are only faintly defined. Posterior antennse and oral parts agreeing in structure with those in the preceding species. Natatory legs, how- ever, exhibiting some characteristic differences: 1st pair with the outer ramus armed in a manner similar to that in 0. spinirostris, except that the apical spine is less strong and almost setiform; inner ramus apparently only biarticulate, the 2 outer joints being confluent. 2nd and 3rd pairs with no spine outside the middle joint of the outer ramus, though exhibiting at the end of the joint a small dentiform projection of the margin. 4th pair without any spines either on the 1st or 2nd joints. Terminal joint of this ramus in all 3 pairs with only a single small spine outside, attached close to the end, and exhibiting moreover in the 2nd and 3rd pairs a very small dentiform prominence of the margin at about the middle of the joint Ovisacs narrow oblong and closely appressed to the sides of the tail, each sac containing only a single series of very large and pellucid ova. Male closely resembling that of the preceding species, but of smaller size, and moreover differing somewhat in the armature of the natatory legs, the ter- minal joint of the outer ramus having only 2 spines outside. Body in both sexes extremely pellucid, without any obvious pigment. Length of adult female 0.700.90 mm.; of male 0.500.60 mm. Remarks. There cannot in my opinion be any doubt, that the form at first recorded by Glaus as 0. helgolandica is the present species. It has subse- quently been redescribed by the same author from Mediterranean specimens, but under another specific name, viz., similis, and this name has been applied to the present species by most authors. According to the rules of priority, however, the first name under which a species has been recorded should in every case be retained. The 2 forms named by Boeck 0. spinifrons and 0. pyymcea are un- doubtedly both referable to the present species, and this is also the case with the form described by Dr. Giesbrecht from the bay of Kiel as 0. spinirostris. The present species is easily distinguishable from the preceding one by the rather different form of the rostrum, the less elongated anterior antennae, and the very different manner in which the ovisacs are borne by the female. Also in the struc- ture of the natatory legs some well-marked differences are found to exist, as shown in the above diagnosis. Occurrence. This form occurs very abundantly along the whole coast of Norway, both on the outer shores and in the fjords. In the Christiania Fjord I have often taken it in great numbers even close to the beach of the innermost shallow creeks. As with the preceding species, male specimens are much scarcer than females, and seem only to appear in certain seasons. Distribution. The distribution of this species seems to be very extensive. It has been noted as far north as in Mosel Bay, Spitsbergen, and southwards in the Mediterranean, off the Canary Islands, and even in the Indian Ocean. I have myself examined specimens taken off the coast of New Zealand, and have care- fully compared them with northern specimens, without having been able to detect any difference whatever. Fam. 2. Cyclopinidae. Characters. Body of somewhat varying shape, but never so slender as in the Oithonidce, the anterior division being, as a rule, considerably dilated. Head in most cases confluent with the 1st trunk-segment; rostral projection short and generally bent in against the ventral face. Anterior antennae less elongated than in the Oithonidse, tapered, and clothed with moderately long seta?; those in male strongly hinged. Posterior antennae generally composed of 4 joints. Oral 2 Crustacea. 10 parts well developed and on the whole built on the same type as in the Calanoida. Natatory legs comparatively short and stout, with both rami 3-articulate and subequal in length. Last pair of legs generally extended laterally and composed of 1 3 joints. Remarks. The type of this family is the genus Cyclopina of Glaus, which has generally been considered as closely allied to Cyclops, but which in reality differs very essentially in the structure of the oral parts, which much more resembles that found in the Calanoida. 4 different genera referable to this family will be described in the sequel. Gen. 2. CyClOpina, Glaus 1863. Generic Characters. General form of body much resembling that in the genus Cyclops. Anterior antennae more or less elongated and composed of a somewhat varying number of articulations ; posterior antennae distinctly 4- articulate. Mandibles with the cutting edge divided into a number of sharp claw- like denticles, palp comparatively large, biramous, inner ramus well developed, biarticulate, outer generally niultiarticulate. Maxillae with the masticatory lobe well defined and armed with several claw-like spines, palp lamellar, with both outer appendages sharply defined and carrying long plumose setae. Anterior maxillipeds rather stout, with the 2nd basal joint clawed, and the terminal part well developed, consisting of 3 joints. Posterior maxillipeds more slender, with the terminal part generally divided into 3 or 4 setiferous joints. Natatory legs of normal structure. Last pair of legs extended laterally, and composed of 2 or 3 joints, none of which are lamellar. Remarks. This genus was established in the year 1863 by Glaus, to include a species, C. gracilis, found by him at Messina. The genus is chiefly characterised by the Cyclops-like form of the body, and by the very full devel- opment of the mandibular and maxillary palps, which strongly recalls that in the Calanoida. Several species have been recorded by different authors; but some of these have turned out to be referable to other genera, not even belonging to the present family. In the succeeding pages 4 different species of this genus, belonging to the fauna of Norway, will be described, and I am much disposed to believe that their number will be considerably increased by a closer study of our Copepod-fauna. For instance, many years ago, off the Lofoten islands, I observed 2 peculiar forms, the one distinguished by the excessive prolongation of the 11 caudal rami, the other by the strong development of the spines on the legs. The specimens of these 2 forms, which I had noted with the provisory names, C. longifurca and C. euacantha, have, however, unfortunately been lost, and I am thus unable to give any closer description of them here. A small species of this genus has also been described by me from the Chatham Islands under the name of C. pusilla, and another species has recently been recorded by Th. Scott as C. longicaudata. 3. Cyclopina graeilis, Claus. (PI. IV). Cyclopina gracilis, Claus, Die freilebenden Copepoden, p. 104, PI. X, figs. 9 15. Syn: Cyclopina norvegica, Boeck. Cyclops salinm, Brady. Specific Characters. Female. Body moderately slender, with the anterior division oval in form, greatest width exceeding half the length and occurring about in the middle. Tail rather slender, with the genital segment about the length of the other 3 combined and gradually narrowed behind. Caudal rami of somewhat varying length, though scarcely longer than the last 2 segments combined, sub- linear in form and only slightly diverging, seta of outer edge placed in front of the middle ; apical setae of moderate length, the inner medial one being, as usual, the longest and about equal to the tail in length ; seta of inner corner scarcely longer than that of the outer. Anterior antennas not much elongated, being considerably shorter than the cephalic segment, and composed of 10 joints, the 6th of which is much the longest and about equal in length to the 4 succeeding ones combined. Posterior antennae with the last joint scarcely as long as the 2nd. Natatory legs with the spines outside the outer ramus of moderate size, 3 such spines being present on the terminal joint, except in 4th pair, where only 2 spines occur outside the apical spine. Last pair of legs biarticulate, proximal joint comparatively broad and finely ciliated inside, carrying outside the usual slender bristle, distal joint shorter and narrower than the proximal one, sub- quadrangular in form, and armed on the obtusely truncated extremity with 2 somewhat unequal lanceolate spines, between which a slender bristle is attached. Ovisacs of moderate size, oval in form, and carried closely appressed to the sides of the tail. Male of much smaller size than female, and easily distinguished by the strongly hinged anterior antennae and the distinctly 5-articulate tail, the 1st (genital) segment of which is considerably dilated. Last pair of legs of exactly the same appearance as in the female. 12 Body in both sexes of a whitish grey colour, with a faint yellow tinge. Length of adult female 0.43 0.57 mm. Remarks. This form was rather imperfectly described by Glaus from Mediterranean specimens, and has subsequently been observed by other authors in different places of the northern Ocean. The form recorded by Boeck as C. norvegica can scarcely be regarded as specifically distinct, though it represents a strictly littoral variety, with the caudal rami comparatively shorter than in the typical form. Dr. Giesbrecht has also called attention to the variation in this respect both in the present and next species. The Cyclops salinus of Brady is unquestionably the present species, and belongs to its variety norvegica, Boeck. The specific name gracilis proposed by Glaus for the present species, is some- what inappropriate, since in reality this species is of less slender form of body than most of the other known species. Occurrence. I have taken this form in several places on the Norwegian coast, from the Christiania Fjord at least up to the Trondhjem Fjord. It is a strictly littoral form, being found close to the shore among algse and scarcely ever, like the next species, at any considerable depth. The variety norvegica occurs rather frequently in shallow creeks and in pools left by the tide, both on the southern and western coasts. Distribution. British Isles (Brady), coast of France (Canu), bay of Kiel (Giesbrecht), Franz Josef Land (Scott), Polar Islands north of Grinnel Land (2nd Frain Expedition), Mediterranean (Glaus), Black Sea (Czerniawsky). 4. Cyclopina longieornis, Boeck. (PI. v). Cyclopina longicornis, Boeck, Nj'e Slsegter og Arter af Saltvandscopepoder. Clir. Vid. Selsk. Forhandl. 1872, p. 41. Syn: Cyclopina littoralis, Brady. Specific Characters. female. Body comparatively more slender than in the preceding species, with the anterior division oblong oval in form, greatest width about equalling half the length and occurring in the middle, cephalic segment gradually tapered anteriorly, with the front narrowly rounded. Tail very slender, almost equalling in length the anterior division, genital segment sligthly dilated in front and shorter than the 3 succeeding segments combined. Caudal rami long and narrow, being generally longer than the 2 preceding segments combined, seta of outer edge rather slender and attached a little in front of the middle; apical setse very unequal, the inner medial one equal to the whole tail in length and fully twice as long as the outer, seta of outer corner scarcely half as long 13 as the inner. Anterior antennae much more elongated than in the preceding species, about equalling in length the cephalic segment, and composed of 18 well defined joints, 3rd joint much the largest, 6th joint exhibiting a slight indication to be subdivided into 3 joints. Posterior antennae with the terminal joint fully as long as the 2 preceding joints combined. Natatory legs with the seta attached inside the 1st joint of the inner ramus remarkably strong, especially in the 2 posterior pairs; terminal joint of outer ramus in 4th pair with only a single spine outside, the distal spine being replaced by a thin bristle abruptly bent inwards. Last pair of legs of comparatively feeble structure, and composed each of 3 joints, the first 2 somewhat lamellar and finely ciliated inside, middle joint carrying outside the usual bristle, last joint comparatively small, and provided with 4 slender ciliated setae, the innermost of which is the shortest. Ovisacs of moderate size and slightly divergent. Male, as usual, smaller than female, and easily recognizable by the strongly hinged anterior antennae. Last pair of legs differing from those in female in being 4-articulate, the last joint being subdivided into 2 well defined joints, the proximal of which carries on each side a seta, whereas the distal joint has 4 setse on the tip. Body semipellucid, with scattered opaque patches of a whitish or yellow colour, in some cases, moreover, exhibiting a fine rosy tinge on several parts of the body, as also partly on the anterior antennae. Length of adult female 0.70 0.90 mm. Remarks. This form has generally been recorded under the specific name littoralis proposed by Brady. As, however, the name longicornis, assigned to this species by Boeck, dates from the very same year, and is a much more adequate name, I have found it suitable to prefer that name to the one proposed by Brady. For the present species cannot in reality be said to be, like the preceding one, a strictly littoral form, as it more generally occurs in greater depths and is only quite occasionally met with in the littoral region. I have found that such specimens are of smaller size and have the caudal rami less elongated than in the typical form, thus more properly constituting a particular variety, for which the name littoralis may be retained. The present species is easily distinguished from the preceding one by the more slender form of the body, the much more elongated anterior antennae, and the somewhat different shape of the caudal rami. In the structural details also some well-marked differences are found, especially as regards the structure of the last pair of legs. Occurrence. I have found this form rather frequently in many places of 14 the Norwegian coast, from the Christiania Fjord at least up to the Trondhjem Fjord. It is generally met with in depths ranging from 10 to 60 fathoms, espe- cially where the bottom consists of coarse sand; much more seldom it is found in shallower water among algse. Like the other species of the present genus, it is a true bottom-form, keeping constantly close to the ground. When disturbed, it darts away with great rapidity, to settle again very soon in another place. I have never seen it moving freely for any length of time in the water. Distribution. British Isles (Brady), Cuxhaven (Tim in), Mediterranean (Giesbrecht), Polar Islands north of Grinnel Land (2nd Fram Exped.). 5. Cyclopina brevifurea, G. 0. Sars, n. sp. (PL VI). Specific Characters. Female. Body moderately slender, with the anterior division oblong oval in form, greatest width scarcely exceeding half the length, front evenly rounded. Tail not attaining half the length of the anterior division, genital segment comparatively large, being fully as long as the 3 succeeding seg- ments combined, anal segment shorter than the preceding one. Caudal rami very small, being scarcely longer than they are broad, seta of outer edge slender and attached about in the middle, apical setse rather elongated, the inner medial one considerably exceeding the length of the tail and, like the outer, clothed in its proximal part with coarse distant hairs, seta of outer corner unusually slender, being fully as long as that of the inner corner. Anterior antennas comparatively longer and more slender than in C. gracilis, though not quite attaining the length of the cephalic segment, and composed of 12 well-defined joints, the 6th of which is much the largest, the 6 outer joints short and all of equal size. Posterior antennse with the terminal joint about the length of the antipenultimate one. Natatory legs about as in C. gracilis. Last pair of legs, as in that species, bi- articulate, distal joint, however, comparatively larger, exceeding in length the proximal one, and narrow oblong in form, inner edge finely ciliated, tip armed with 2 slender and somewhat unequal spines, having between them a slender bristle Ovisacs of moderate size, oval in form, and borne closely appressed to the sides of the tail. Body rather pellucid, of a whitish gray colour, with light bluish trans- parent ovaria. Length of adult female 600.70 mm. Remarks. This form is closely allied to C. gracilis Glaus, but differs conspicuously in the shape of the anterior division of the body, the more slender 15 and distinctly 12-articulate anterior antennae, and the remarkably short caudal rami, which latter character has given rise to the specific name here proposed. Occurrence. I have met with this form in several distant places on the Norwegian coast, for instance at Ris0r on the southern coast, at Skutesnses on the south-western coast, and at Bejan outside the Trondhjem Fjord. A single well-marked ovigerous specimen was found, moreover, in a sample taken by Mr. Nordgaard in the Porsanger Fjord, Finmark. The specimens observed by rne were taken in depths ranging from 10 to 30 fathoms, muddy bottom. 6. Cyclopina elegans, Scott. (PI. VII). Cyclopina elegans, Th. Scott, Addition to the Fauna of the Firth of Forth. 12th Ann. Eeport of the Fishery Board of Scotland. Part. Ill, p. 237, PI. V, figs. 919. Specific Characters. Female. Body very slender, with the anterior division narrow oblong in form, greatest width not attaining half the length and occurring in its anterior part, front evenly rounded. Tail almost as long as the anterior division and having the genital segment unusually large and tumid, clothed on each side with small spikes; anal segment fully as long as the preceding one. Caudal rami long and slender, equalling in length the last 2 segments combined; outer edge with 2 successive bristles, the smaller one occurring at a short distance form the base, the other attached nearer to the end and somewhat dorsally ; apical seise of moderate length, that of the outer corner shorter than that of the inner. Anterior antennae moderately slender, though not attaining the length of the cephalic segment, and composed of 18 joints, the 4th and 5th joints exhibiting, however, a more or less distinct sub-division, so that the number of joints may be increased to 20 21. Posterior antennae with the terminal joint scarcely longer than the antipenultimate one. Mandibular palp comparatively more slender than in the other species, with the outer ramus shorter. Posterior maxillipeds with the terminal part composed of 5 well-defined joints. 1st pair of legs, like the 3 succeeding ones, provided with 2 setse inside the middle joint of the inner ramus, these setae being in 4th pair very coarse, almost spiniform. Last pair of legs distinctly 3-articulate. 1st joint with a coarse ciliated seta inside, middle joint rather dilated and carrying outside the usual slender bristle; terminal joint nar- row oblong in form, exceeding in length the other 2 combined, and provided outside with 2 setee, at the tip with another very slender seta and a stout spine. Ovisacs of moderate size and somewhat divergent. 16 Colour whitish grey, with a slight yellow tinge. Length of adult female about 0.80 mm. Remarks. This is a very distinct species, easily recognisable both by the general form of the body and by the structure of some of the appendages. Occurrence. The only place where I have observed this species, is at Farsund, south coast of Norway. It occurred here occasionally together with C. longicornis in a depth of about 20 fathoms, sandy bottom. Distribution. Firth of Forth (Scott), Gulf of Naples (Giesbrecht). Gen. 3 CyClOpinella, G. 0. Sars, n. Generic Characters. General appearance resembling that in the genus Cyclopina, the anterior division of the body being considerably dilated, the posterior narrow and attenuated. Head defined from the 1st pedigerous segment by a well-marked suture. Anterior antennae comparatively short and composed of a limited number of articulations. Posterior antennae with the first joint simple and quite smooth. Mandibles short and stout, with the palp less fully developed than in Cyclopina, being simple, without any outer ramus. Maxilla? likewise rather short, palp with the 2 outer appendages well developed and of about equal size, one of the apical spines, as also those of the masticatory lobe, unusually thick, almost digitiform. Anterior maxillipeds rather compact, with the claw of the 2nd basal joint scarcely different from the spines of ihe terminal part. Posterior maxillipeds much smaller, and of the usual structure. Natatory legs well developed differing somewhat in structure from those in Cyclopina. Last pair of legs less rudimentary than usual, being distinctly 3-articulate, with the terminal joint comparatively large and armed with strong lanceolate spines. Remarks. This new genus is somewhat allied to Cyclopina, though dis- tinguished by certain apparently fundamental differences, of which may be named the distinct separation of the head from the 1st pedigerous segment, and the simple structure of the mandibular palp. Only a single species of this genus has hitherto come under my notice. 7. Cyclopinella tumidula, G. 0. Sars, n. sp. (PL VIII). Specific Characters. Female. Body comparatively short, with the anterior division greatly tumefied and almost pyriform in shape, the greatest width occurring 17 far in front and considerably exceeding half the length. Tail very narrow and tapered, with the genital segment only slightly dilated, anal segment fully as long as the preceding one. Caudal rami somewhat exceeding in length the anal seg- ment and narrow linear in form, seta of outer edge attached about in the middle, apical setse rather unequal, the inner medial one, as usual much the longest and about equalling in length the tail; seta of outer corner quite rudimentary, that of inner attaining the length of the corresponding ramus and very thin. Eye wholly absent. Anterior antennae much shorter than the head, and composed of 12 well-defined joints, the 9th of which is somewhat longer than the others and carries a slender sensory filament. Posterior antennse with the terminal joint unusually short, not even attaining the length of the preceding one. Mandibular palp forming a simple bi-articulate stem, the distal joint of which is very small and provided with 3 curved setse. Natatory legs with no seta inside the 1st joint of the outer ramus; 1st pair with a strong spine outside the terminal joint of the inner ramus, re- placing the usual seta; spines of outer ramus in this and the succeeding pairs slender, and edged with hyaline rims, 4 such spines being present on the terminal joint in the 3 anterior pairs, 3 in that of the 4th pair, inner ramus of the latter pair unusually narrow and, like that of the 2 preceding pairs, armed at the tip with 2 spines. Last pair of legs with the 1st joint quite unarmed, 2nd carrying outside a slender bristle, terminal joint much longer than the other 2 combined, oblong quadrangular in form, and much constricted at the base, carrying outside, somewhat in front of the middle, a strong lanceolate spine and at the transversely truncated end 2 similar spines and a very small bristle between them, inner edge of the joint straight and finely ciliated. Ovisacs small, and borne closely appressed to the sides of the tail, each containing, as a rule, only 3 ova arranged in a single row. Male exhibiting the usual sexual characters. Last pair of legs of exactly the same appearance as in female. Body of the usual whitish grey colour, but appearing darker on account of the translucent, very capacious anterior part of the intestine, which is generally filled with dark brown contents. A peculiar opaque body of a whitish or pale orange hue, and transversely oval or semilunar in form, is constantly found im- mediately inside the dorsal wall of the head, in front of the intestine, and is very conspicuous in the living animal. 1 ) Length of adult female 0.68 0.75 mm. *) 1 am unable to say anything about the significance of this body. It cannot be the missing visual organ, as it does not occupy the usual place of the eye, being far remote from the front. As to structure, it seems to consist of a uniform granular matter. 3 Crustacea. 18 Remarks. In its general appearance this form is rather similar to certain species of the genus Cyclopina, and I was indeed at first inclined to refer it to that genus. The closer anatomical examination has, however, proved it to be in reality so different, that in my opinion it ought to be generically separated. Occurrence. I have met with this peculiar form in several distant places on the Norwegian coast, for instance at Ris0r and Lillesand on the southern coast, at Christiansund on the western coast, and in the Trondhjem Fjord. In all places it occurred on a muddy bottom, partly covered by decaying algae, the depth ranging from 20 to 40 fathoms. Gen. 4. CyelOpetta, G. O. Sars, n. Generic Characters. Body somewhat depressed, with the 2 chief divisions less sharply marked off from each other than in the 2 preceding genera. Head confluent with the 1st pedigerous segment, and conspicuously contracted in front. Tail comparatively short. Anterior antennae of inconsiderable length, with the number of articulations reduced. Posterior antennae likewise unusually short and stout, and clothed with strong plumose setae. Mandibles with the palp distinctly biramous, outer ramus well developed, inner uniarticulate. Maxillae and maxilli- peds very small and difficult to examine, though apparently built on the same type as in the other Cydopinidce. Natatory legs well developed and of normal structure. Last pair of legs consisting each of a single lamellar joint edged with ciliated setae. Remarks. This new genus in some respects differs rather conspicuously from the 2 preceding ones, and seems to exhibit a certain approach to the next anomalous genus, Pterinopsyllus, though it is distinguished also from this genus by several well-marked characters. The genus is only founded upon a single species, to be described below. 8. Cyclopetta diffieilis, G. 0. Sars, n. sp. (PI. IX). Specific Characters. Female. Body comparatively short and stout, and distinctly depressed, with the anterior division oblong fusiform in outline, greatest width scarcely exceeding half the length, and occurring about in the middle. Cephalic segment rather large and evenly contracted anteriorly, with 19 the front narrowly rounded. Tail not attaining half the length of the anterior division, and scarcely tapering behind; genital segment conspicuously constricted in the middle, anal segment equalling in length the 2 preceding ones combined. Caudal rami short, not nearly attaining the length of the anal segment, and quadrangular in shape, seta of outer edge attached about in the middle, apical setae of moderate length, the inner medial one about twice as long as the outer, both coarsely ciliated, seta of outer corner much smaller than that of the inner. Anterior antennae scarcely exceeding half the length of the cephalic segment, and each composed of only 9 joints clothed with strong partly ciliated setae ; 5th joint the longest, 6th about the length of the 3 outer joints combined. Posterior antennae distinctly 4-articulate, 1st joint provided at the end on either side with a strong ciliated seta, 2nd joint with a similar seta in front, 3rd joint with 4 such setae outside, last joint about the length of the 2 preceding ones combined, and car- rying on the tip 6 anteriorly-curving and likewise densely ciliated setae. Man- dibular palp with the outer ramus composed of 4 well defined joints, inner ramus with 3 ' comparatively short apical setae. Proximal outer lobe of the maxillary palp much larger than the distal one and carrying 4 unusually thick plumose setae. Maxillipeds very small and densely crowded, the anterior ones apparently of normal structure, the posterior ones with the number of the terminal joints much reduced. Natatory legs not exhibiting any pronounced peculiarity in their structure. Last pair of legs consisting each of a rounded oval lamella attached outside the last trunk-segment and provided with 3 thick and curved ciliated setae; just above this lamella a thin bristle is attached to a conical projection of the segment itself. Colour not yet ascertained. Length of adult female 0.60 mm. Remarks. The present form cannot be confounded with any of the other Cyclopinida 1 , exhibiting, as it does, a most characteristic appearance, somewhat recalling that found in certain of the semi-parasitic forms, to which, indeed, I was at first inclined to refer it, before having made out its anatomy. Occurrence. Only 3 specimens of this remarkable form, all of the female sex, have hitherto come under my notice. They were picked up from a sample taken last summer at Riser, south coast of Norway, in a depth of about 40 fathoms, muddy sand. All 3 specimens have been sacrified for dissection, in order to get a satisfactory conception of the structure of the very small and densely crowded oral parts. The specific name here proposed alludes to the difficulty experienced in the examination of these parts.- 20 Gen. 5. PterlnOpSyllUS, Brady, 1880. 83-11 : Lopliophorus, Brady (not Temminch). Cyclopella, Claus. Generic Characters. Body robust and somewhat depressed, with the anterior division moderately dilated, the posterior less narrow than usual. Head coalesced with the 1st pedigerous segment, and terminating in a blunt rostrum projecting downwards. Caudal rami short, with the 2 middle apical setae very strong and densely ciliated. Anterior antennae short and stout, with the number of articulations reduced, and clothed with unusually strong pennate setae ; those of male of much larger size and strongly hinged. Posterior antennae likewise short, and only 3-articulate, the last 2 joints being united. Mandibles with the cutting part considerably expanded and coarsely dentate; palp comparatively slender, with the outer ramus small and undivided, inner raraus biarticulate. Maxillae with all the constituting parts well developed. Anterior maxillipeds very stout, with 3 well-defined terminal joints armed with strong spines. Posterior maxillipeds with the terminal part very fully developed and composed of 5 joints, the 1st much larger than the others. Natatory legs strongly built, with short and blunt spines outside the outer ramus; inner ramus of 1st pair in male pre- hensile, that of 4th pair more or less reduced in female, normal in male. Last pair of legs comparatively small and not extended laterally, being composed of 3 more or less lamellar joints, somewhat different in the two sexes. Remarks. This genus was established in the year 1878 by Prof. Brady, to comprise a peculiar Copepod found by him off the British coast. As, however, the generic name he proposed, Lopliopliorus, had been preoccupied for a genus of birds, he changed it in the year 1880 to Pterinopsyllas. The name Cyclopella proposed by Claus is of later date, and must yield to that given to the genus by Brady. The systematic position of the present genus has remained somewhat doubtful. In some respects it recalls certain genera among the Harpacticoida, and, indeed, it has been placed within that group in the list of Crustacea from Northumberland and Durham published by Norman and Brady. I think, however, that its place within the group Cyclopoida cannot at present be disputed. On the other hand, owing to the peculiarities observed in this genus, it might be thought necessary to establish for its reception a distinct family. Pteriiiopsyllidos. Indeed, I was at first much inclined to do so ; but after having become acquainted with the preceding genus, Cyclopetta, which in some respects exhibits an evident 21 approach to the one here under consideration, I find that, without any serious scruple, it may be included in the family Cyclopinidce, as here defined. In addition to the typical species described below, 2 closely-allied species, P. egregius and P. illustris, have been recorded by Dr. Giesbrecht from the gulf of Naples. 9. Pterinopsyllus insignis, Brady. (PI. X & XI). Lophophorus insignis, Brady, Monograph of British Copepoda, Vol. I, p. 122, PI. XIII, figs. 1 10, PI. XV, fig. 10. Specific Characters. Female. Body rather stout, with the anterior division ovate in outline, greatest width exceeding half the length and occurring about in the middle. Cephalic segment large and narrowly produced in front. Last trunk-segment sharply defined from the preceding one, and projecting laterally in a small dentiform process. Tail about half the length of the anterior division, and nearly of uniform width throughout; genital segment about as long as the 3 succeeding ones combined, and scarcely at all dilated in front; anal segment shorter than the preceding one. Caudal rami quadrangular in shape, being scarcely longer than they are broad, seta of outer edge obsolete, the 2 middle apical setse very strong and divergent, with coarser and more scattered hairs on their proximal parts, seta of outer corner much smaller than that of the inner, both very thin and naked. Anterior antennae scarcely more than half as long as the cephalic segment and rather broad at the base, being composed of 8 joints, the 2nd of which is the largest, 5th joint very small. Posterior antennae clothed along the outer edge and at the tip with coarsely hairy setse, inner edge without any setse. 4th pair of natatory legs with the inner ramus much shorter than the outer, middle joint imperfectly defined from the terminal one and without any setse inside, the latter joint having inside 2 short blunt spines replacing the usual setae. Last pair of legs with the 1st joint imperfectly defined at the base, but carrying inside a well-developed ciliated seta, 2nd joint conically produced out- side and carrying the usual thin bristle, last joint much larger than the other 2 combined, and forming a rounded oval lamella coarsely ciliated inside and provided with 4 slender setse, 3 of which are ciliated, the 4th, issuing from the tip, very thin and smooth. Ovisacs. according to Brady, short pyiiform, with a limited number of ova. Male of smaller size than female, and easily recognisable by the very coarse structure of the anterior antennse, which are powerful prehensile organs divided into 12 joints. Inner ramus of 1st pair of legs with the apical spine 22 peculiarly transformed, being abruptly bent, so as to form a claw-like prehensile appendage. Inner ramus of 4th pair of quite normal structure. Last pair of legs as in the female, 3-articulate; the 1st joint does not, however, answer to the 1st joint in the female, but to the 2nd, as is clearly shown by the bristle issuing from its outer side. Of the other 2 joints, which accordingly answer to the terminal joint in the female, the proximal one is much the larger and carries at the end on each side a seta, whereas the distal joint is quite short with 4 diverging setae on the end. Body in both sexes of a whitish grey colour, with a slight violaceous tinge. Eye in living specimens very conspicuous and of light red colour. Remarks. The present form may be easily recognised from any of our indigenous Cyclopoida, both by its characteristic outward appearance and by the rich ornament of coarsely-ciliated setae, which clothes most of the appendages. Especially are these setse very conspicuous on the anterior antennae, where they partly assume a pennate or pectinate character, giving these appendages a peculiar shruppy appearance. It was indeed to this peculiarity that the generic name, Lophopkorus, at first proposed by Brady, alluded. From the 2 Mediterranean species recorded by Dr. Giesbrecht the present form cannot be distinguished without a very close anatomical examination. Occurrence. I have met with this pretty form occasionally in 3 different places on the Norwegian coast, viz., in the inner part of the Christiania Fjord, at Ris0r, and at Flekker0, outside Christiansand. The specimens were taken in depths ranging from 20 to 40 fathoms, muddy sand. Canon Norman has taken this form also in the Trondhjem Fjord, at R0dberget, where it occurred in the considerable depth of 150 fathoms. Distribution. Coast of England and Scotland (Brady, Scott), Gulf of Naples (Giesbrecht). Fam. 3. Cyclopidae. Characters. General form of the body resembling that in the typical Cyclopinidce, the anterior division being more or less dilated, the posterior much narrower and attenuated. Head in all the known forms confluent with the 1st pedigerous^segment, and having the rostrum bent in against the ventral face. Anterior antennae more or less elongated and strongly hinged in male. Posterior antennae generally 4-articulate, with an elongated seta at the end of the 1st joint 23 posteriorly. Anterior lip with the terminal edge finely denticulate. Mandibles with the palp quite rudimentary, being reduced to a small knob-like process carrying 2 or 3 ciliated setae. Maxillae with the palp likewise imperfectly devel- oped and without any distinctly-defined outer appendages. Maxillipeds built on the same type as in the Cyclopinidce, but of comparatively simpler structure. Natatory legs, as a rule, well developed, with subequal triarticulate rami, though in some instances the number of joints in the rami may be reduced. Last pair of legs generally small and of the same appearance in the two sexes. Remarks. This family, in the restriction here adopted, is chietiy distin- guished from the 2 preceding ones by the rudimentary condition of both the mandibular and the maxillary palps. This character is invariably found in all the forms, and must be regarded as of fundamental significance. In other respects this family exhibits a close resemblance to the Cyclopinidce. Only a limited number of species, belonging to 2 genera, are strictly marine, whereas in fresh water we find a great number of forms, all generally referred to a single genus, viz., Cyclops. I have, however, found it appropriate to divide this extensive genus into a number of closely-allied genera (or sub- genera), which will be characterised in the next parts of the present Volume. Gen. 10. Euryte, Philippi, 1843. Syn : Thorellia, Boeck. Generic Characters. Body, as a rule, rather robust, the anterior division being considerably tumefied, and sharply marked off from the slender and attenuated tail. Anterior antennas in female divided into a great number of short, but well- defined joints; those in male much more strongly built, and hinged in the usual manner. Posterior antennse rather stout, 4-articulate, with the last 2 joints comparatively short. Mandibles with the cutting edge divided into several sharp claw-like teeth, setse on the rudimentary palp not much elongated. Maxilla? with the masticatory lobe well developed and armed with strong dentiform spines, palp forming an oblong lamella projecting beyond the masticatory lobe and terminating in a serrated edge, being moreover provided on each side with 2 juxtaposed setaa. Anterior maxillipeds rather stout, with the digitiform lobe, issuing from the end of the 1st basal joint anteriorly, comparatively strong and, like the 2nd basal joint, projecting in a claw-like spine accompanied by a much 24 thinner seta; terminal part composed of only a single joint armed with short curved spines. Posterior inaxillipeds of a somewhat unusual appearance and apparently sub-prehensile, the terminal part being abruptly bent and terminating in 2 short claw-like spines. Natatory legs powerfully developed with broad flattened basal part and the joints of the rami partly conspicuously expanded; spines of outer ramus lanceolate, bordered by broad hyaline rims finely serrated at the edges; several of the setse, both of this and the inner ramus, transformed to similar, though more delicate spines. Last pair of legs less rudimentary than usual, and resembling in structure those in the genus Cydopinella. Remarks. This genus was established by Philippi as early as in the year 1843, but was not recognised by Boeck, who records it under another name, viz., Thorellia. The genus is especially characterised by the peculiar structure of the maxillary palp and that of the posterior maxillipeds, as also by the trans- formation of several of the natatory setse on the legs to lanceolate spines. Two species of this genus have hitherto been described, both occurring off the Nor- wegian coast, and a 3rd new species is here added. All 3 species are exclusively marine. 10. Euryte longieauda, Philippi. (PI. XII). Euri/tc longicauda, Philippi, Fernere Beobachtungen iiber die Copepoden des Mittelmeeres. Arch. f. Naturg. 1843, p. 63, PI. 3, fig. ad. Sjn : Thorellia brunnea, Boeck. Cyclops, nigricauda, Norman. Cyclopina Clausi, Czerniawsky. Specific Characters. Female. Anterior division of body rounded oval in outline, greatest width almost equalling 2 /s of the length, and occurring somewhat behind the middle. Cephalic segment very large, considerably longer than all the free trunk-segments combined, and evenly rounded in front. Last trunk- segment somewhat produced on each side. Tail very slender, almost attaining the length of the anterior division ; genital segment imperfectly subdivided in the middle, and exhibiting on each side a dentiform posteriorly-pointing projection; anal segment longer than the preceding one. Caudal rami very slender and elongated, equalling in length the last 3 segments combined, and sublinear in form, diverging a little in their distal parts, which appear slightly thickened; seta of outer edge attached near the extremity ; apical setse not much elongated, the inner medial one not nearly attaining the length of the tail, that of the outer corner shorter than that of the inner. Anterior antennse rather slender, though 25 not quite attaining the length of the cephalic segment, and composed of 21 joints, the 1st of which is much the largest; 2nd joint faintly subdivided in the middle. Posterior antennse rather strongly built, 2nd joint angularly produced at the end inside, and almost as long as the outer 2 joints combined, some of the apical setse rather strong, almost spiniform. 1st pair of natatory legs with the inner corner of the 2nd basal joint considerably produced and carrying a strong de- flexed spine; middle joint of inner ramus very broad and, like that of the suc- ceeding pairs, provided inside with 2 setse, terminal joint with all the setee trans- formed to spines. Setse of terminal joint of outer ramus in 2nd to 4th pairs likewise transformed. Last pair of legs with the 1st joint very small and imper- fectly defined at the base, 2nd joint likewise rather small, and carrying outside the usual bristle, last joint comparatively large, oblong quadrangular in shape and somewhat curved at the narrowed base, being armed with 3 strong lanceolate spines, one of which issues a little beyond the middle of the outer edge, the other 2 from the transversely truncated extremity; between the latter, moreover, a thin bristle is attached. Ovisacs narrow oblong in form and greatly diverging. Male, as usual, smaller than female and of somewhat more slender form of body, being moreover easily recognised by the strongly hinged anterior antennae and the distinctly 5-articulate tail. Colour yellowish brown, with scattered patches of a darker hue; proximal part of the caudal rami and the middle part of the anterior antenna? generally of a similar dark hue. Length of adult female about 1.30 mm., that of male 0.90 mm. Remarks. The identity of the above-described form with Philippi's Eurytc longicauda has been sufficiently proved by Dr. Giesbrecht, who observed the species in about the same place, that Philippi had made his investigations in. The name Thorellia brunnea, under which this species has been recorded by most authors, is of much later date than- that given to this form by Philippi, and can- not therefore be retained. It is also beyond doubt that both Cyclops nigricauda Norman and Cyclopina Clausi Czerniawsky are referable to the same species. From the 2 next species the present one may be easily distinguished by the very long and slender caudal rami, as also by the manner in which the ovisacs are borne in the female. Occurrence. I have found this form rather plentifully along the whole Norwegian coast, from the Christiania Fjord to Vads0 in moderate depths among algae. More particularly it seems to haunt places where the great Laminaria? grow, to the leaves of which it is often found clinging rather firmly, probably by the aid of the clawed posterior maxillipeds. It moves through the water 4 Crustacea. 26 in the usual jumping manner, and has on the whole in its behaviour much the appearance of an ordinary Cyclops. Dr. Scott records a smaller form of this species, which he designates as varietas minor. I have also myself in the inner part of the Christiania Fjord observed such small, though fully adult specimens, but have failed to detect any other differences from the typical form. Distribution. British Isles (Brady), coast of France (Canu), Gulf of Naples (Philippi), Black Sea (Czerniawsky), eastern coast of Greenland (Buchholtz), Franz Josef Land (Scott), Polar Islands north of Grinnel Land (2nd Fram Expedition). 11. Euryte robusta, Giesbrecht. (PI. XIII). Euryte robusta, Giesbrecht, Mittheilungen iiber Copepoden, 12 14, p. 58, PI. 4, figs. 1 18. Specific Characters. Female. Body comparatively more robust than in the preceding species, with the anterior division more regularly oval in outline. Tail comparatively shorter and broader at the base ; genital segment exhibiting in the middle quite similar dentiform projections to those in E. longicauda. Caudal rami rather shorter than in that species, scarcely exceeding in length the last 2 segments combined, and slightly diverging at the end; apical seta3 more evenly ciliated, Anterior antennae, as in that species, rather slender and composed of 20 joints. Posterior antennae somewhat less robust, with the 2nd joint scarcely angular behind and the apical setae thinner. Posterior maxillipeds with the apical claws more slender and accompanied by 2 thin bristles. Structure of the legs almost exactly as in E, longicauda, though having the spines comparatively shorter and stouter. Ovisacs small and of irregularly rounded form, each containing a very limited number of ova. Male resembling that of the preceding species, bat of somewhat more robust form. Body of a dark ochraceous colour, the caudal rami being tinged with deep chestnut and the anterior antenna with bands of a similar hue. Length of adult female 1.20 1.40 mm., of male about 1.00 mm. Remarks. I cannot doubt that the above-described form is identical with that recorded by Dr. Giesbrecht from the gulf of Naples, though there are a few points of disagreement. Thus Dr. Giesbrecht counts 21 joints in the anterior antenna?, whereas I have never found more than 20 such joints, some of which even are imperfectly defined. The figure given by him of the posterior antennae also differs somewhat, and more agrees with those antennae in E. longicauda. Otherwise, however, the two forms seem to agree perfectly. 27 The present species is closely allied to E. longicauda, but is easily distinguished by the comparatively more robust form of the body, and more particularly by the considerably shorter caudal rami. Occurrence. I have found this form not unfrequently in several places of the Norwegian coast, for instance at Eleven and Korshavn on the southern coast, and at Aalesund and Christiansund on the western coast. It is a more pronounced deep-water form than the preceding one, being generally found in depths ranging from 20 to 60 fathoms, especially where the bottom consist of coarse sand inter- mingled with mud. It is very perplexing, that this form has not yet been ob- served off the British Isles, the Copepod-fauna of which has been so thoroughly studied, especially by Th. Scott. Distribution. Gulf of Naples (Giesbrecht). 12. Euryte curticornis, G. 0. Sars, n. sp. (PI. XIV). Specific Characters. Female. Body somewhat less robust than in the preceding species, with the anterior division ovate in outline, the cephalic segment being somewhat contracted in front. Last trunk-segment less produced laterally than in the other 2 species. Tail exceeding somewhat half the length of the anterior division, genital segment with only a slight rudiment of the lateral denticles so conspicuous in the 2 preceding 1 species. Caudal rami about equalling in length the last 2 segments combined, and not at all diverging, tapering slightly distally; apical setae of moderate length, the 2 middle ones clothed in their prox- imal part with rather coarse and distant hairs. Anterior antennas much shorter and thicker than in the 2 preceding species, though composed of a similar great number of joints (20), most of the setae rather coarse and finely ciliated. Posterior antennae of a similar structure to that in E. robusta. Posterior maxillipeds less abruptly curved and having the terminal part much shorter, with the apical claws extremely minute. Natatory legs built in the same manner as in the 2 preceding species, though having the rami somewhat less broad and the spines more slender. Last pair of legs likewise of a very similar structure, last joint, however, com- paratively shorter. Ovisacs rather large, and borne closely appressed to the sides of the tail. Colour not yet ascertained. Length of adult female 1.30 mm. Remarks. This new species may be at once distinguished from the 2 preceding ones by the much shorter an stouter anterior antennae, which character 28 indeed has given rise to the specific name here proposed. In the structural detail also some minor differences are found to be present, especially as regards the posterior maxillipeds and the caudal rami. Occurrence. Several specimens of this form were collected, many years ago, at Skraaven, Lofoten islands. They occurred in a depth of about 6 fathoms, on a sandy bottom partly overgrown with algse. Gen. 11. HaliCyClOpS, Norman, 1903. Syn : Hem-icy clops Glaus (not Boeck). Generic Characters. Body of the usual cyclopoid shape, and somewhat depressed in its anterior part. Head confluent with the 1st pedigerous segment, and having the rostrum bent in against the ventral face. Anterior antennae short, with the number of joints greatly reduced; those in male strongly hinged. Posterior antennae with the outer 2 joints confluent. Mandibles with one of the cutting teeth much larger than the others, setse of rudimentary palp comparatively short. Maxillary palp forming a small lamella not extending beyond the masticatory lobe, and terminating in a short spine accompanied by one or two setse. Anterior maxillipeds with the digitiform lobe, issuing from the end of the 1st basal joint anteriorly, rather small and terminating in 2 unequal setse. Posterior maxillipeds imperfectly developed, being composed of 2 or 3 joints only. Natatory legs built upon the usual cyclopoid type, but having the rami not nearly so broad as in Euryte. Last pair of legs with the proximal joint more or less completely coalesced with the corresponding segment, distal joint broad lamelliform and edged with partly ciliated setse. Remarks. This genus was established in the year 1893 by Glaus, to include the form generally recorded as Cyclops ce-qvoreits Fischer. As, however. the name he proposed, Hemicy clops, had been preoccupied by Boeck, to designate another very different genus, not even belonging to the same section, it has been changed by Norman to Halicy clops. The genus is nearly allied to Cyclops, but differs in the imperfect development of the posterior antennae and of the posterior maxillipeds, as also in the peculiar structure of the last pair of legs. In addition to the typical form, to be described below, another nearly-allied species has been recorded by the present author from the Ghatam islands as H. propinqvus, and a 3rd species, not yet described, occurs, as a true planktonic form, in the Caspian 29 Sea. All the species are inhabitants of more or less brackish water, though they may be of marine origin, as they are never found in purely fresh water. 13. Halicy clops magniceps (Lilljeborg). (PI. XV). Cyclops magniceps, Lilljeborg. De crustaceis ex ordinibus tribus, etc. p. 204, PI. XXII, fig. 1. 83-11: Cyclops ceqroreus, Fischer. christianiensis, Boeck. Specific Characters. Female. Body moderately stout, with the anterior division oblong oval in outline, greatest width about equalling half the length and occurring somewhat in front of the middle. Cephalic segment very large and broadly rounded in front; last trunk-segment only slightly produced laterally. Tail scarcely more than half as long as the anterior division, genital segment nearly of equal width throughout, anal segment shorter than the preceding one, and deeply cleft at the end. Caudal rami about twice as long as they are broad and somewhat divergent; seta of outer edge attached about in the middle; apical setse rather slender, the inner medial one attaining half the length of the body; seta of outer corner shorter than that of the inner. Anterior antennas compara- tively short and stout, being composed of only 6 distinctly defined joints, the first 2 rather dilated, the 3rd quite short, the 4th nearly as long as the outer 2 joints combined. Posterior antenna with the terminal joint sub-fusiform in shape, and provided in the middle outside with a well-marked notch, indicating the place where the 2 outer joints have been coalesced. Posterior maxillipeds very small and only composed of 2 joints, the distal one much the smaller. Natatory legs with the terminal joint of the inner ramus not much larger than the middle one, and provided in the 1st pair with 2, in the other pairs with 3 spines in addition to the setse; terminal joint of outer ramus having 3 spines outside in the 3 anterior pairs, 2 in the 4th pair. Last pair of legs with the proximal joint imperfectly defined from the segment, distal joint much expanded, spatulate in form, terminal edge obliquely truncated and carrying 4 comparatively short setas, the innermost but one simple, the others ciliated. Ovisacs oblong oval in form and borne closely appressed to the sides of the tail, each containing only a limited number of ova. Male much smaller than female, and having the anterior antenna? very strongly built, being composed of 1 1 more or less distinctly defined joints, the last consituting the terminal section and produced in a sharp point. Last pair of legs with the proximal joint more distinctly defined, distal joint only differing 30 from that in female by the presence of an additional seta attached inside the others. Body semipellucid, of a whitish colour, with a very faint yellowish or greenish tinge. Ovaria and ova in the ovisacs generally of a dark blue colour. Length of adult female 0.75 mm. Remarks. This form was first recorded by Lilljeborg under the name of Cyclops magniceps, but was rather imperfectly described, and, as moreover the number of joints in the anterior antennae were erroneously indicated to 8, instead of 6, the species was not recognised by subsequent authors, who generally recorded it under the specific name ceqvoreus proposed by Fischer several years afterwards. The form named by Boeck Cydop christianiensis is also unquestionably the same species. It is distinguished from the nearly-allied form H. propinqvus G. 0. Sars by the more produced caudal rami, as also by its larger size. Occurrence. I have found this form not unfrequently in the uppermost part of the Christiania Fjord, where it occurs close to the border of the shallow creeks in the immediate neighbourhood of the town. It also occurs in other places, both of the south and west coasts of Norway, partly in more or less brackish water. Distribution. Kullaberg, coast of Sweden (Lilljeborg), British Isles (Brady), coast of France (Canu), Algeria (Richard), Madeira (Fischer). Gen. 12. CyClOpS, Miiller, 1776 (ex parte). Generic Characters. Anterior division of body moderately tumid, and generally more tapered behind than in front; lateral parts of the 3 anterior trunk- segments well denned and sub-angular behind; last trunk-segment more or less produced laterally. Tail slender and attenuated, with the genital segment in female more or less dilated in front. Anterior antennae of varying length, and more generally composed of 17 well defined joints, though in some cases, by concrescence, their number may be considerably reduced ; those in male strongly hinged, with the terminal section distinctly biarticulate. Posterior antennae with all 4 joints well defined, the 1st carrying at the end posteriorly a long ciliated seta. Rudimentary palp of the mandibles carrying 2 very long and densely plumose setae accompanied by a short bristle. Maxillary palp scarcely extending beyond the masticatory lobe, and provided outside near the base with 4 ciliated setre, 3 of which issue from a slight expansion of the margin. Anterior maxilli- 31 peels moderately strong, with the 1st basal joint generally subdivided in the middle, and provided anteriorly with a small rounded lobe carrying 2 plumose setae; digitiform lobe issuing from the end of this joint anteriorly comparatively small, with none of the setse unguiform. Posterior maxillipeds much more slender, and composed of 4 well-defined joints. Natatory legs with both rami generally 3-articulate. though in some cases, by an imperfect separation of the 2 outer joints, one or other of them, or all, may be only biarticulate ; inner ramus of 4th pair with 2 apical spines. Last pair of legs very small and generally not extended laterally, being composed of 2 joints, the proximal of which in some cases may be coalesced with the corresponding segment, distal joint not expanded, and carrying a slender apical seta and a short lateral spine. Seminal receptacle in female of compara- tively simple structure, being generally transversely oval in shape. Remarks. This genus is here taken in a much more restricted sense than done by other authors. Owing to the great number of species referred to this genus, it has long appeared very desirable to group them according to their mutual relationship, in order to get a clear survey on them. A such grouping of the European species has indeed been effected by Dr. Schmeil in his very valuable work on the fresh water Copepoda of Germany. I think, however that we may be justified to take a further step, and to subdivide the old genus Cyclops into a number of nearly-allied genera, each being designated by a particular name. In the present work I have attempted to do so, distinguishing 5 different genera, the name Cyclops being restricted to one of them, which comprises the greater bulk of the hitherto known species. In this genus I have included 4 of the 8 groups of Cyclopses distinguished by Dr. Schmeil, having not found sufficient reason for a generic separation of these groups; the 4 other genera answer to as many groups distinguished by Dr. Schmeil. In the restriction here adopted, the present genus is, among other things, characterised by the well defined and angular epimeral parts of the segments composing the anterior division of the body, giving to the sides of that division a more or less jagged appearance. Of the structural details, it is especially the rudimentary last pair of legs which exhibits a very characteristic appearance, conspicuously differing from that in any of the other 4 genera. A considerable number of species referable to the present genus will be described in the sequel, some of them being, however, so closely allied, that their specific distinctness has not generally been recognised. They all, like the species of the 4 succeeding genera, are exclusive inhabitants of fresh water. 32 The diagnoses here given of the several species have chiefly been drawn up from adult female specimens, the males affording, as a rule, no particular characters availble for the specific distinction. 14. Cyclops strenUUS, Fischer. (PI. XVI). Cyclops strenuus, Fischer, Bulletin tie la Societe Imper. d. Nat. de Moscow, Vol. XXIV, p 419 PI. IX, figs. 1221. Syn . l ) ? Monoculus qvadricornis rubens, Jurine. ? Cyclops pictus, Koch. qvadricornis, Lilljeborg. brevicaudatus, Glaus. Clausi, Lubbock. Specific Characters. Female. Body moderately slender, with the anterior division oblong oval in form, greatest width about equal to half the length and occurring in the middle. Cephalic segment only slightly longer than the 4 suc- ceeding segments combined, and narrowly rounded in front. Lateral parts of penultimate trunk-segment terminating in a short tooth-like projection turned somewhat outwards. Last trunk-segment angularly produced laterally. Tail some- what exceeding half the length of the anterior division ; genital segment conspicu- ously dilated in front, though the width is somewhat less than the length. Caudal rami moderately slender, exceeding in length a little the last 2 segments combined, and slightly divergent, being linear in form, and each provided dorsally with a distinct longitudinal keel, inner edge finely ciliated; seta of outer edge rather small and not much remote from the end ; apical setae comparatively short, the inner medial one only very little longer than the outer and scarcely twice as long as the corresponding ramus, seta of inner corner not much longer than that of the outer. Anterior antennse of moderate length, reaching, when reflexed, to the middle of the 2nd segment, and composed of 17 joints. Natatory legs with 3 spines outside the terminal joint of the outer ramus of 1st and 2nd pairs; inner edge of same joint carrying in 1st pair 3, in the succeeding pairs 4 setae. Inner ramus of 4th pair moderately slender, with the outer apical spine some- what exceeding half the length of the inner. Last pair of legs with the distal joint not twice as long as it is broad, lateral spine rather strong and attached about in the middle of the inner edge. Ovisacs comparatively large, oval in form, and borne closely appressed to the sides of the tail. Seminal receptacle transversely truncated in front. *) Many other synonyms have been given in the work of Dr. Schmeil. But as he evidently has combined several species under the name strenuus, only those synonymes are here quoted, which more strictly may refer to the species here under consideration. Oithonidae. Copepoda Cyclopoida. PL I. r. F. G. O. Sars, del. Oithona spinirostris, Claus. Oithonidae. Copepoda Cyclopoida. PL II. G. O. Sars, del. Oithona spinirostris, Claus. (Continued). Oithonigae. Copepoda Cyclopoida. PL III. . ffrt i zr G. O. Sars, del. Oithona helgolandica, Claus. Cyclopinidse. Copepoda Cyclopoida. PI. IV. '' 77 - G. O. Sars, del. Cyclopina gracilis, Glaus. Cyclopinidae. Copepoda Cyclopoida. PI. V. G. O. Sars, del. Cyclopina longicornis, Boeck. Cyclopinidse. Copepoda Cyclopoida. PL VI. G. O. Sars, del. Cyclopina brevifurea, G. O. Sars. Cyclopinidae. Copepoda Cyclopoida. PI. VII. II ' G. O. Sars, del. Cyclopina elegans, Scott. Cyclopinidse. Copepoda Cyclopoida. PI. VIII. ' > G. O. Sars, del. Cyclopinella tumidula, G. O. Sars. Cyclopinidse. Copepoda Cyclopoida. PL IX. T G. O. Sars, del. Cyclopetta difficilis, G. O. Sars. Cyclopinidae. Copepoda Cyclopoida. PL X. ;*#? v ^ - G. O. Sars, del. Pterinopsyllus insignis, Brady. Cyclopinidse. Copepoda Cyclopoida. PI. XI. ft G. O. Sars, del. Pterinopsyllus insignis, Brady. (Male) Cyclopidse. Copepoda Cyclopoida. PI. XII. G. O. Sars, del. Euryte longicauda, Philippi . Cyclopidse. Copepoda Cyclopoida. PI. XIII. fy* **'>*., "" ~ / 1~] G. O. Sars, del. Euryte robusta, Giesbr. Cyclopidse. Copepoda Cyclopoida. PI. XIV. G. O. Sars, del. Euryte curticornis, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XV. ,' \ r- r - G. O. Bars, del. Halicyclops magniceps (Lilljeb.). Cyclopidae. Copepoda Cyclopoida. PI. XVI. i G. O. Bars, del. Cyclops strenuus, Fischer. AN ACCOUNT OF THE CRUSTACEA OF NORWAY WITH SHORT DESCRIPTIONS, AND FIGURES OF ALL THE SPECIES BY G. O. SARS VOL. VI COPEPODA CYGLQPOIDA PARTS III & IV CYCLOPID^E (continued) WITH l(i AUTOTYP1C PLATES BERGEN PUBLISHED BY THE BERGEN MUSEUM SOLD BY i . ALB. CAMMEEMEYER'S FOELAG, .CHEISTIANIA 1913 33 Colour generally light yellow or orange. Length of adult female 1.50 1.70 mm. Remarks. The present species is in all probability identical with the form named by Jurine Monoculus quadricornis rubens, and also Cyclops pictus of Koch may be the same species. As, however, some doubt might arise about the identity, this species has generally been recorded under the name proposed by Fischer, who indeed was the first to give a recognisable description of it. Both C. brevicaudatus, Claus and C. Clausi, Lubbock are undoubtedly referable to the present species, which may be regarded as the type of the genus Cyclops as defined here. Occurrence. This is one of our commonest Cyclopses, being very abundant in small ponds and tarns, especially early in the spring. It is not. like most other species of the present genus, a strict bottom-form, but is generally found close to the surface of the water, swimming about rather quickly in the usual jumping manner. Male specimens are at first rather scarce, but become more numerous later in the season. Two varieties occur, the one of rather smaller size than the other and of lighter colour, and found in somewhat larger tarns. I have, however, failed to detect any other difference between the 2 forms. Distribution, Throughout Europe, central and northern parts of Asia, Bear Island, Spitsbergen, Algeria. 15. Cyclops abyssorum, G. 0. Sars. (PI. XVII). Cyclops abyssorum, G. 0. Sars, Oversigt af tie indenlandske Ferskvandscopepoder. Chr. Vid. Selsk. Forhandl. 182, p. 29. Syn. : C. strenuus, var. temdpes, G-. 0. Sars. Specific Characters. Female. Body comparatively more robust than in C. strenuus, with the anterior division more tumefied in its anterior part. Cephalic segment obtusely rounded in front. Lateral parts of penultimate trunk- segment terminating in a well-marked dentiform point curving outwards. Last trunk- segment acutely produced laterally. Genital segment considerably dilated in front, its greatest width exceeding the length. Caudal rami very slender and narrow, exceeding somewhat in length the last 3 caudal segments combined, and rather divergent, each having dorsally a very distinct longitudinal keel, inner edge coarsely ciliated, seta of outer edge small and attached near the end, apical setse com- paratively longer and thinner than in C. strenuus, the inner medial one almost attaining the length of the tail, seta of inner corner twice as long as that of the outer. Anterior antennae much more slender and elongated than in C. strenuu*, 5 Crustacea. reaching, when reflexed, considerably beyond the 2nd segment, and having some of the marginal setae rather slender. Posterior antennae with the terminal joint longer than the penultimate one and much narrower. Anterior maxillipeds with the claw of the 2nd basal joint comparatively longer than in C. strenuus. Nata- tory legs having the same number of spines and setse as in that species, rami, however, considerably more slender, especially those of 4th pair; apical spines of inner ramus in this pair more elongated, the outer one about half as long as the inner. Last pair of legs with the proximal joint comparatively less broad than in C. strenuus, distal joint about twice as long, and having the lateral spine of moderate size and attached nearly in the middle of the inner edge. Ovisacs smaller than in the preceding species and rounded oval in form, each containing a rather limited number of ova. Seminal receptacle comparatively small, with the anterior part evenly rounded. Colour whitish grey, with a slight yellow tinge more distinct on the tail. Length of adult female 1.80 1.90 mm. Remark*. The above-described form is closely allied to C. strenuus, and has indeed by most recent authors been regarded as only a variety of that species. We know, however, at present of several species exhibiting a similar close relation- ship to C. strenuus, and together forming a natural group of Cyclopses. All of these have, it is true, been combined by Dr. Schmeil in a single species; but in recent time, the specific distinctness of some of these forms has been fully recog- nized. Thus Lilljeborg, in his account of the Swedish Cyclopses (1901), de- scribes as well-defined species the 2 forms C. scutifer, G. 0. Sars and C. vic'mus, Uljanin, which are both recorded by Dr. Schmeil as only synonyms of C. strenuus. Though Lilljeborg was inclined to regard the present form as merely a "luxuri- ant" deep-water variety of C. strenuus, it is in my opinion fully as distinct from that form as are the 2 just-named species. On a closer comparison, it is in reality found to differ conspicuously from C. strenuus, both as to its outward appear- ance and the structure of some of the appendages. Among more easily observable differences I may mention the greater length of the anterior antennae, the very narrow form of the caudal rami, and the somewhat different mutual relation in the length of the apical setae. It may moreover be noted here, that the form of the seminal receptacle, on which Dr. Schmeil laid so much stress for the discrimination of species, is in the present species rather different from that in C. strenuus, as shown by the figures given in the 2 respective plates. The form recorded by me from the lake Telecki in Altai as C. strenuus, var. gracilipes, I now find to be more properly referable to the species here under consideration. 35 Occurrence. I first found this species in the Mariclal Lake near Christiania, where it occurred only in the deepest part of the lake, at the considerable depth of 40 50 fathoms; hence the specific name proposed. Prof. Brady has taken it under quite similar circumstances in some 'of the British lakes. Besides in the Maridal Lake, I have observed this form in the Vansj0, near Moss, and in the Stensfjord, a branch of the great lake, Tyrifjord. In the last-named locality it occurred rather frequently at depths varying from 6 to 12 fathoms, muddy bottom. The specimens from all 3 localities agree perfectly with each other, and the figures given by Prof. Brady show the British form also to be in full accordance with the Norwegian one. Distribution. Sweden (Lilljeborg), British Isles (Brady), Central Asia (the present author). 16. Cyclops lacustris, G. 0. Sars. (PI. XVIII). Cyclops lacustris, G. 0. Sars, 1. c., p. 30. Specific Characters. Female. Body moderately slender, with the anterior division oblong oval in form, greatest width about half the length and occurring somewhat in front of the middle. Cephalic segment comparatively large, with the frontal part almost transversely truncated. Lateral parts of penultimate trunk- segment not at all produced, being of the very same appearance as in the 2 preceding segments. Last trunk-segment likewise only very slightly prominent laterally. Uenital segment of a rather characteristic form, being considerably longer than it is broad and abruptly narrowed in the middle, with the anterior part moderately dilated, the posterior part cylindric in shape. Caudal rami not attaining the length of the 3 preceding segments combined, and slightly divergent, dorsal keel obsolete, inner edge very finely ciliated, seta of outer edge small and not very far from the end, apical setse rather slender, the inner medial one attaining fully the length of the tail, seta of inner corner more than twice as long as that of the outer. Anterior antennae rather slender, reaching, when reflexed, beyond the 2nd segment of the body. Anterior maxillipeds with the claw of the 2nd basal joint unusually slender. Natatory legs exhibiting an arma- ture similar to that in the 2 preceding species, rami comparatively slender, with very long setae; outer apical spine of inner ramus in 4th pair rather small, scarcely exceeding 1 / 3 of the length of the inner. Last pair of legs with the distal joint rather narrow, sublinear in form, lateral spine extremely minute and attached at about the middle of the inner edge, apical seta, on the other hand, 36 unusually long and slender. Ovisacs small, rounded, and each containing a very limited number of ova. Seminal receptacle comparatively larger than in C. abys- sornm, anterior part evenly rounded, posterior part rather produced. Spermatophores attached to the genital opening of about the same appearance as in C. strenuus. Body highly pellucid, with a very faint bluish or greenish tinge. Length of adult female 1.50 mm., of male 1.30 mm. Remark*. In the case also of the present form the specific validity has not been admitted by recent authors, though in my opinion it is a very well-defined species. Lilljeborg was inclined to regard it as a variety of C. strenuus, which has adapted itself to a limnetic life. On a closer examination, however, the well-marked differences which this form exhibits cannot by any means be explained in this way, nor be regarded as simply accidental or varietal. Occurrence. I have only met with this form in our 2 largest lakes, Mjoseri and Tyri fjord. It lives there as a true limnetic form together with Lhnno- calanus mac-mi-u* and other midwater forms, being generally found swimming about close to the surface of the water. Distribution. Sweden (Lilljeborg). 17. Cyclops scutifer, G. 0. Sars. (PI. XIX). ' '//clops scntifer, G. 0. Sars, 1. c,, p. 28. Specific Clici meters. Female. Body comparative!}^ slender, with the anterior division narrow oblong in outline, greatest width scarcely attaining half the length, and occurring somewhat in front of the middle. Lateral parts of the last 2 trunk-segments greatly produced, being expanded to triangular exstant lamellse, which are more or less contiguous, so as to present, together with the corresponding segments, the appearance of a quadrangular shield obtecting the posterior part of the trunk. Genital segment comparatively large and very much dilated in front, with a small knob-like prominence on each side, posterior part gradually narrowed. Caudal rami scarcely longer than the last 2 segments combined and only very slightly divergent, dorsal keel only faintly indicated, inner edge finely ciliated ; seta of outer edge rather remote from the end, apical setae very unequal in length, the inner medial one much the longest, seta of inner corner more than twice as long as that of the outer. Anterior antennae rather slender, reaching, when reflexed, considerably beyond the 2nd segment of the body, and clothed with comparatively long setae. Posterior antennse with the terminal joint scarcely longer than the penultimate one. Anterior maxillipeds resembling in 37 structure those in C. lacustris. Natatory legs armed as in the 3 preceding species, rami moderately slender, the inner one in 4th pair with the outer apical spine very small; spines of outer ramus in all pairs rather thin; seta attached inside the 1st basal joint in 4th pair much coarser than in the other pairs. Last pair of legs with the proximal joint comparatively small, distal joint more than twice as long, with the lateral spine of moderate size and attached somewhat beyond the middle. Ovisacs generally very small, rounded, each containing a very limited number of ova. Seminal receptacle of moderate size and evenly rounded both in front and behind. Spermatophores attached to the genital opening unusually large, projecting beyond the side of the genital segment Body highly pellucid and generally almost colourless, in some cases, however, exhibiting a beautiful emerald green hue. Length of adult female 1.20 1.40 mm, of male 1.10 mm. Remarks. This form was considered by Dr. Schmeil as only a variety of C. strenuus : but Lilljeborg has subsequently, in his account of the Swedish Cy- clopses, vindicated its specific distinctness. It is especially recognisable by the extraordinary development in the female of the epimeral plates on the last 2 trunk-segments, which gives the body a rather characteristic appearance and has indeed given rise to the specific name scutifer. Occurrence. I have met with this form rather abundantly in several of our larger lakes, for instance in the Maridal and Lut Lakes near Christiania, where it lives as a true limnetic form. It also occurs in mountain lakes at the limit of perpetual snow, and is indeed the only Crustacean to be found there. Distribution. Sweden (Lilljeborg), Northern part of Siberia (the present author). 18 Cyclops vicinUS, Uljanin. (PI. XX). Cyclops vidims, Uljanin, Crustacea <>t' the Expedition of A. Fedtschenko in Turkestan (in Russian). ]>. 30, PI. X, figs. 1 7. Syn.: Cyclops strenuus, Schmeil (not Fischer). pulchellus, Brady (not Koch). Specific Characters. Female. Body moderately slender, with the anterior division oblong oval in form and somewhat tumefied in front. Lateral parts of penultimate trunk-segment produced in the form of acutely triangular extant lappets; those of last segment likewise produced, though less so than in 6'. scutifer. Genital segment about as long as it is broad at the base, and gradually narrowed behind. Caudal rami long and slender, equalling in length the last 3 segments 38 combined, and only slightly divergent, dorsal keel well marked, inner edge minutely ciliated; seta of outer edge not very far from the end, apical setae not much elongated, the inner medial one about twice the length of the ramus, seta of inner corner more than twice as long as that of the outer. Anterior antennae comparatively shorter and stouter than in the preceding species, reaching, when rerlexed, scarcely beyond the middle of the 2nd body-segment; number of joints generally only 16, the 8th and 9th joints being contiuent. Posterior an- tennae with the terminal joint a little longer and narrower than the penultimate one. Natatory legs with the rami moderately slender, terminal joint of outer ramus in all pairs with only 2 spines outside; outer apical spine of inner ramus in 4th pair very small and rudimentary. Last pair of legs resembling in shape those in C. slrennus, the distal joint being rather short and stout, with the lateral spine well developed and attached about in the middle. Ovisacs of moderate size and oval in shape. Seminal receptacle comparatively small, resembling that in C. cibyssorum. Colour, according to Lilljeborg, somewhat variable, the body being in some cases of a unitorm whitish grey hue, in other cases tinged with brownish red or reddish yellow. Length of adult female about 1.70 mm. Remarks. This form was first described by the Russian naturalist Uljanin, but was subsequently considered by Dr. Schmeil to be only a variety of C. strain us. Its specific distinctness has, however, been vindicated by Lillje- borg, and I have myself, by an examination of specimens from Mongolia, had an opportunity of confirming this view. The habitus-figure given in Dr. Schmeil's work, as pointed out by Lilljeborg, evidently refers to this species, and also the form described in Prof. Brady's Monograph as C. pulchellus, is unquestionably referable to the same species. The most conspicuous character distinguishing this form from C. strain ns is the very prominent lateral parts of the last 2 trunk-segments, in which respect it somewhat resembles C. scutifer. It differs, however, very markedly both from this and the 3 other species described above, in the armature of the natatory legs, the terminal joint of the outer ramus having in all pairs only 2 spines outside. Occtti-rciice. This form, it is true, has not yet been observed within the limits of our country ; but I cannot doubt that, on a closer investigation, it will be found to occur at any rate in the south-eastern part of the country, since Lilljeborg has recorded it from immediately adjacent tracts of Sweden. The figures here given are from specimens found in a sample taken in the delta of 39 the Volga, and kindly sent to me for examination from the Zool. Museum of St. Petersburg. Distribution. Sweden (Lilljeborg), British Isles (Brady), Germany (Schmeil), Turkestan (Uljanin), Mongolia and Mouth of Volga (the present author). 19. Cyclops insignis, Glaus. (PI XXI). Cyclops insignis, Clans, Weitere Mittheilungen iiber Cyclopiden, Arch. Nat. Hist. '23 Jahrg. Bd. 1, p. 209, PI. XI, figs. 8 IB. Syn.: Cyclops quadricornis, Kocli. Specific Characters. Female. Body rather slender, though having the anterior division somewhat dilated and of regularly elliptical form, its greatest width somewhat exceeding half the length and occurring in the middle. Lateral parts of penultimate trunk-segment not produced, and of same shape as those of the 2 preceding segments. Last trunk-segment rather broad and sharply pointed on each side. Tail slender and attenuated, though shorter than the anterior division; genital segment very broad in front and abruptly constricted behind. Caudal rami long and slender, considerably exceeding in length the last 3 seg- ments combined, and narrow linear in form, being only very slightly divergent, each ramus exhibiting dorsally a very distinct longitudinal keel; seta of outer edge somewhat remote from the end, apical set;e not much elongated, the inner medial one being scarcely more than twice as long as the ramus, seta of inner corner very little longer than that of the outer, which is rather strong, almost spiniform. Anterior antennse of moderate length, reaching, when reflexed, about to the middle of the 2nd segment of the body, and composed of only 14 joints, the 8th to 1 1th joints being coalesced into a single elongate segment. Posterior antennse with the terminal joint scarcely longer than the penultimate one. Nata- tory legs more strongly built than in the preceding species, terminal joint of outer ramus in all of them having only 2 spines outside ; outer apical spine of inner ramus in 4th pair less rudimentary, exceeding half the length of the inner. Last pair of legs with the distal joint rather narrow and somewhat constricted near the base, lateral spine of moderate size and attached about in the middle. Ovisacs large, oval, and carried closely appressed to the sides of the tail. Seminal receptacle short and broad, of a somewhat irregular transversely elliptical form and not produced behind. Spermatophores attached to the genital opening placed at right angles to the axis of the body. Colour yellowish, with a more or less distinct olivaceous tinge. Length of adult female amounting to 2.60 mm. 40 Remarks This is an easily recognisable species, though, according to the structure of the several appendages, it seems to be referable to the same group as the 4 preceding species. It is, however, at once distinguished from them by its much larger size, the 14-articulate anterior antennae, the peculiar shape of the genital segment, and the long and slender caudal rami. The C. qvadricornis of Koch seems to be this species; but as the name qvadricornis is a collective one, it cannot be maintained. The form recorded by Brady as C. insignis is scarcely that species. Occurrence. I have taken this form in great numbers early in the spring from ponds near Christiania. Later in the summer it was not observed. Distribution. Sweden (Lilljeborg), Germany (Schmeil), Bohemia (Fric). 20. Cyclops vulgaris, Koch. (PI. XXII). Cyclops vulgaris^ Koc.li, Dentsclilands Omstaceen, Myriopoden und Arachniden, Heft 21, Tab. 4. Syn.: MonocuJus urctdrironris ririrlis, Jurin^. Cyclops viridis, Fischer, lft^ Clans. Specific Characters. Female. Body comparatively robust, with the anterior division rather dilated and broadly oval in form, greatest width considerably exceeding half the length Cephalic segment very large and broadly rounded in front. Lateral parts of penultimate trunk-segment of same appearance as those of the 2 preceding segments. Last trunk-segment only slightly produced laterally. Tail scarcely exceeding half the length of the anterior division; genital segment moderately dilated in front and gradually narrowed behind. Caudal rami scarcely longer than the last 2 segments combined, and only very slightly diverging, without any dorsal keel, but with the inner edge finely ciliated; seta of outer edge not very far from the end, middle apical setae rather elongated, the inner one attaining half the length of the body; seta of inner corner more than twice as long as that of the outer. Anterior antennae not very slender, being scarcely longer than the cephalic segment, and composed of the usual number of joints (17). Posterior antennae with the terminal joint longer than the penulti- mate one. Anterior maxillipeds more strongly built than in the preceding species. Natatory legs likewise rather strong; terminal joint of outer ramus in all of them with only 2 spines outside, inner edge of same joint in the 1st pair with only 2 setse, in the other pairs with 3 setae ; apical spines of inner ramus in 4th pair of almost equal size. Last pair of legs with the proximal joint unusually broad and conically produced outside, distal joint very small, with the lateral spine extremely minute and rudimentary. Ovisacs large, fusiform in shape, and con- 41 siderably divergent. Seminal receptacle with the anterior part transversely ellip- tical in form and sharply defined from the posterior part, which is exserted on each side to a band-like stripe. Colour rather variable, in some cases bluish green, in other cases with a distinct olivaceous tinge, and not uncommonly light whitish grey, with dark patches at the end of the segments. Length of adult female amounting to 1.90 mm. Remarks. This form has generally been recorded under the name C. viridis Jurine. I consider it, however, to be scarcely admissible to appropriate as specific designations the several varietal names appended by Jurine to his species Monoculus qvadrieornis and merely indicating the diversity in colour found by him in different specimens. As moreover the colour both in the present species and in several other Cyclopses is rather variable, the Jurinian names would in fact be of very little significance to the species. The form recorded by Koch as C. vulgaris is unquestionably this species, and as the name riri'ibi joy clops, especially P. fimbriat'iis (Fischer). It is, however, a genuine Cyclops, as shown by the struc- ture of the legs, and in this respect closely approaches the 2 preceding species. Occurrence. Some specimens of this pretty form were taken last summer in Mj0sen, near Hamar, from a depth of 4 6 fathoms, muddy bottom. According to Lilljeborg, it descends in some instances to considerably greater depths, having been found by that author in one of the Swedish lakes (Ifsjo) down to 25 fathoms. It was indeed for this reason that the specific name ab/jssicola was proposed. Distribution. Sweden (Lilljeborg). 31. Cyclops varieans, G. 0. Sars. (PI. XXXIII). Cyclops raricans. G. 0. Sars, 1. c.. p. 43. Syn.: Cyclops orientalis, Uljanin. Specific Characters. Female. Body not very slender, with the anterior division oval in form, greatest width somewhat exceeding half the length and _55_ occurring about in the middle. Cephalic segment comparatively large and evenly rounded in front. Last trunk-segment somewhat produced laterally. Tail only slightly exceeding half the length of the anterior division ; genital segment con- spicuously dilated in front and gradually narrowed behind. Caudal rami about the length of the last 2 segments combined and scarcely divergent ; seta of outer edge somewhat remote from the apex, middle apical setse rather slender, the inner one considerably longer than the outer, and about equalling in length the tail and last trunk-segment combined ; seta of inner corner very thin, though consider- ably longer than that of the outer. Anterior antennae comparatively short, not attaining the length of the cephalic segment, and only composed of 12 joints. Posterior antennse with the last joint scarcely longer than the penultimate one. Anterior maxillipeds short and stout, with the claw of the 2nd basal joint almost straight. Natatory legs with both rami in all the pairs biarticulate, 4th pair, in the living animal, generally projecting to each side of the trunk; inner ramus of this pair with both apical spines well developed, the outer one about half as long as the inner. Last pair of legs with the proximal joint wholly confluent with the segment, its seta springing off from the lateral corner, distal joint small, narrow conical in form, and having an extremely minute spinula in the middle of the inner edge, apical seta rather slender. Ovisacs comparatively large, oblong in form, and somewhat divergent. Seminal receptacle small, rounded, exserted on each side to a narrow band-like stripe. Colour whitish, with a fainte yellow or reddish tinge. Length of adult female 0.700.90 mm. Remarks. This species, together with the succeeding one. is included by Dr. Schmeil in a particular group of Cyclopses (his varicans-bicolor group), chiefly characterised by the biarticulate rami on all the natatory legs, and the imperfect development of the last pair of legs. The same characters are also exhibited by some exotic Cyclopses. Thus, of the several species described by the present author from the lake Tanganyika, Central Africa, C. attenuatus, C. Cunningtoni and C. pacliycomns belong to this group. The same is also the case with the Australian species, C. Arnaudi, G. 0. Sars. Finally the form recorded by Dr. Lepeschkin as C. diaphanus, var. dengizica represents another species of the said group. According to the statement of Dr. Schmeil the C. orientalis ofUljaninis identical with the present species, and I am also of opinion, that the C. rubel/n* of Lilljeborg can hardly be distinguished specifically. Occurrence. This form seems to be of rare occurence in our country. I have only met with it in some grassy ponds near Christiania. The specific name varicans alludes to the peculiar manner in which the 4th pair of natatory legs are borne in the living animal, these legs being constantly extended laterally to each side of the trunk, without apparently partaking in the movements of the other pairs. Distribution. Sweden (Lilljeborg), Germany (Schmeil), Poland (Lande), Turkestan (Uljanin), Central Africa (Gr. 0. Sars), New Zealand (G. 0. Sars), North America (Her rick). 32. Cyclops bicolor, G. 0. Sars. (PI. XXXIV). Cyclops bicolor. G. 0. Sars. 1. c., \>. 44. Syn.: Cyclops dbaphanus, Rehberg (not Fischer). Specific Character*, Female. Body comparatively short and stout, with the anterior division oval in form, greatest width slightly exceeding half the lenght and occurring about in the middle. Last trunk-segment less produced laterally than in C. rriricdnx. Tail rather slender, equalling 2 /o of the length of the anterior division ; genital segment only slightly dilated in front and gradually tapered behind, its anterior parts rather protuberant below. Caudal rami about the length of the last 2 segments combined and of linear form, being not at all divergent; seta of outer edge not far from the apex, the 2 middle apical setse remarkably thick and densely covered with cilia, the inner one only slightly longer than the outer and much shorter than the tail; seta of inner corner about twice as long as that of the outer and much thinner. Anterior antennae still shorter than in C. raricans, only slightly exceeding half the length of the cephalic segment, and composed of only 11 joints. Posterior antennae with the last joint considerably longer than the penultimate one. Maxillipeds agreeing in structure with those in C. varwans. Natatory legs, as in that species, with both rami in all the pairs biarticulate ; 4th pair rather smaller than the preceeding pairs, and having the rami comparatively narrow, outer apical spine of inner ramus very small and rudimentary, inner spine long and slender. Last pair of legs still more reduced than in C. varicans, its proximal joint wholly coalescent with the segment, distal joint extremely small, without any trace of a lateral spine. Ovisacs of moderate size and carried closely appressed to the tail. Seminal receptacle transversely ellipti- cal in form and almost occupying the whole width of the genital segment. Colour rather peculiar, the anterior division of the body being, as a rule, nearly colourless, whereas the whole tail and the anterior antennae exhibit a beautiful golden yellow or orange hue. Length of adult female scarcely exceeding 0.60 mm. Cyclopidse. Copepoda Cyclopoida. Pi. XVII. r. G. O. Sars, del. Cyclops abyssorum, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PL XVIII. /** 're- G. O. Sars, del. Cyclops lacustris, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. Pi. XIX. . \ . : G. O. Sars, del. Cyclops scutifer, G. O. Sars. Cyclopidse. Copepoda Cyclopoida. PI. XX. x r. G. O. Sars, del. Cyclops vicinus, Uljanin. Cyclopidae. Copepoda Cyclopoida. PL XXI. /I \ \ G. O. Sars, del. Cyclops insignis. Claus. Cyclopidae. Copepoda Cyclopoida. PI. XXII. . / I ' f LJ r G. O. Sars, del. Cyclops vulgaris, Koch. Cyclopidae. Copepoda Cyclopoida. Pi. XXIII. G. O. Sars, del. Cyclops gigas, Claus. Cyclopidae. Copepoda Cyclopoida. PI. xxiv. a-' - r-e. G. O. Sars, del. Cyclops capillatus, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PL XXV. (3? G. O. Sars, del. Cyclops lucidulus. Koch. Cyclopidse. Copepoda Cyclopoida. PL XXVI. i G. O. Sars, del. Cyclops robustus, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XXVII. \ : G. O. Sars, del. Cyclops pulchellus, Koch. Cyclopidae. Copepoda Cyclopoida. Pi. XXVIII. G. O. Sars, del. Cyclops bisetosus, Rehberg. Cyclopidse. Copepoda Cyclopoida. PL XXIX. G. O. Sars, del. Cyclops crassicaudis, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. xxx. G. O. Sars, del. Cyclops langvidus, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XXXI. \ <% qeft. ^ V G. O. Sars, del. Cyclops diaphanus, Fischer. Cyclopidae. Copepoda Cyclopoida. PI. XXXII. - i F G. O. Sars, del. Cyclops abyssicola, Lilljeb. AN ACCOUNT OF THE OF NORWAY WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES / BY G. O. SARS VOL. VI COPEPODA GYCLOPOIDA PARTS V & VI CYCLOPIDJE (continued) WITH 1C, AUTOTYP1C PLATES BERGEN PUBLISHED BY THE BERGEN MUSEUM SOLD UY ALB. CAMMKRMEYER'S FORLAG, CHRISTIANIA 191 1 57 Remarks. This form, the smallest of all our Cyclopses. has been con- founded by several authors (Rehberg, Daday, Lande, Richard) with ('. hmi'H* Fischer, from which it differs in many essential points, being much more nearly related to C. varicans. From this latter species it may be easily recognised by its much smaller size, the shorter and only 1 1 -articulate anterior antenna: 1 , and the different structure of the caudal setae, finally by the peculiar colouring of the body when alive. Occurrence. I have only found this form quite occasionally in small grassy ponds near Christiania. In spite of its small size, it may be readily detected, owing to its peculiar and beautiful colour, which character indeed has given rise to the specific name proposed. Distribution. Sweden (Lilljeborg), Germany (Sehmeil), Hungary (Daday), Poland (Lande), France (Richard). Gen. 13. MeSOCyClOpS, U. O. Sars, n. f (Icncrlc Characters. Body more or less slender, with the anterior division generally rather tumid, the posterior very slender. Epimeral parts of the trunk- segments scarcely prominent laterally and, as a rule, not visible in the dorsal aspect of the animal. Last trunk-segment very small, not produced laterally. Genital segment in female rather elongated and very little dilated in front. Caudal rami of moderate length or very short, with all the apical setse generally well deve- loped. Anterior antennae slender and elongated, generally 17-articulate. Posterior antennae likewise slender, with the apical setse long and curved. Maxillipeds rather fully developed. Natatory legs, as a rule, with both rami 3-articulate; terminal joint of outer ramus in all pairs with only 2 spines outside, its inner edge carrying in the 1st pair 2, in the other pairs 3 setae; terminal joint of inner ramus unusually prolonged, especially in the posterior pairs. Last pair of legs very small and generally biarticulate, distal joint carrying 2 slender subequal setse. Seminal receptacle in all the species of a very characteristic form, anterior part short, bilobular, posterior greatly prolonged, tongue-shaped. Remarks. This new genus answers to the group of Cyclopses distinguished by Dr. Schmeil as the "Leuckarti group". The species included in this group differ conspicuously in their external appearance from the more typical Cyclopses described in the preceding pages, and more resemble those belonging to the next genus, Pachycy clops, with which they also agree in the unusually slender form of s Cn.stacea. 58 both pairs of antennae. In the structure of the natatory legs, the unusual prolongation of the terminal joint of the inner ramus is rather characteristic. The last pair of legs are also distinguished by the presence on the distal joint of 2 slender, subequal setae, the inner one replacing the short lateral spine found in the species of Cyclops (sens, strict.). Finally, the very characteristic form of the seminal receptacle may be here mentioned. To the fauna of Norway belong 4 well-defined species, to be described below, and also a number of exotic species may be adduced to the same genus. Thus it is evident that the 2 African species, C. emini Mrazek and C. neglect-it* G. 0. Sars, recorded by the present author in his paper on the Copepoda of the Tanganyika Expedition, are referable to this genus, as is unquestionably the case with the North American species, C. edax Forbes, perhaps also with the South American species, C. sptmfer Daday. I am likewise of opinion that C. yracilis Lilljeborg must be placed within the present genus, in spite of the reduction of the number of joints in the anterior antennae, and the imperfect development of the legs, as this form otherwise has an unmistakable resemblance to the species here under consideration. 33. Mesoeyelops obsoletus (KoHu. (PI. XXXV). C/fckps olsokhtH, Koch, 1. o. Heft 21, Tab. 5. Syn: Cyclops Leuckarti Clans. ,. simplex, Poggenpol. ,. Scourfieldi, Brady. Specific Chanictrr*. Female. Body moderately slender, with the anterior division regularly elliptical in outline, greatest width slightly exceeding half the length and occurring about in the middle. Cephalic segment very large, almost twice the length of the 4 succeeding segments combined. Last trunk-segment very small. Tail slender, exceeding in length 2 /s of the anterior division; genital segment long and narrow, fully attaining the length of the 3 succeeding segments combined, and almost cylindrical in form. Caudal rami of moderate length, though scarcely as long as the last 2 segments combined, and only slightly divergent; seta of outer edge rather far from the apex, being attached a little behind the middle; apical setae comparatively slender and elongated, the inner mediate one attaining the length of the tail, seta of outer corner rather produced, though scarcely half as long as that of the inner. Anterior antennae long and slender, reaching, when reflexed, almost to the end of the 3rd segment, outer joints rather narrow and bordered by a delicate hyaline rib, which on the last joint, at some 59 distance from the end, exhibits a very conspicuous semilunar incision. Posterior antennae likewise unusually slender, with the terminal joint long and narrow. Anterior maxillipeds with the posterior edge of the basal part distinctly crenulated. Posterior pair of maxillipeds of the usual structure. Natatory legs comparatively slender, spines of outer ramus rather coarse, the distal outer spine of the terminal joint apparently issuing from the tip itself, outer edge of the joints very finely spinulose; terminal joint of inner ramus in all pairs unusually prolonged, being fully as long as the other 2 joints combined, setse of inner edge in the 3 posterior pairs rather far from the apex and some of them reduced in size; apical spines of this ramus in 4th pair almost equal-sized; connecting plate of same pair produced behind, on each side, to an acute projection. Last pair of legs with the distal joint rather narrow, both setse very slender and elongated, the inner one somewhat remote from the tip. Ovisacs of moderate size and somewhat diverging. Seminal receptacle exhibiting the form characteristic of the genus, anterior lobes somewhat exserted at the ends, posterior part extending almost to the end of the genital segment. Colour generally pale yellow, with a more or less distinct bluish green tinge. Length of adult female 1.00 1.30 mm. Remarks. I have no doubt that the C. olsoletus of Koch is in reality this species. The figure he gives is rather characteristic, and cannot properly be adduced to any other species. As the specific name proposed by Koch is much older than that given to the species by Glaus, it must be retained for the present form. The C. Scourfielili of Brady is the same species, and according to Dr. Schmeil, C. simplex Poggenpol also is to be regarded as a synonym. Occurrence. - - This is one of our commonest Cyclopids, occurring very abundantly both in small ponds and ditches and in larger lakes. In the latter it lives as a true limnetic form, being found everywhere near the surface of the water together with other limnetic animals. Distribution. Throughout Europe, central and northern parts of Asia, Ceylon, central and southern parts of Africa, North America, Brazil, Patagonia, Australia. The cosmopolitan distribution of this species is very remarkable. 34. Mesocyclops oithonoides, G-. 0. Sars. (PL XXXVI). Cyclops oithonoides, G. 0. Sars. 1. c. p. 32. S\-n : Cyclops hyalinus, Eehberg. Specific Characters. Female. Body very slender, with the anterior division narrow oblong in outline, greatest width not nearly attaining half the length and 1,1) occurring somewhat in front of the middle, Cephalic segment somewhat longer than the 4 succeeding segments combined. Last trunk-segment very small, with the lateral parts ohtusely rounded. Tail attaining vV, of the length of the anterior division: genital segment about equalling in length the 2 succeeding segments combined, and almost cylindrical in form. Caudal rami of moderate length and somewhat diverging, seta of outer edge placed almost in the middle; apical seta? comparatively shorter than in the preceding species, the inner mediate one scarcely exceeding half the length of the tail ; seta of inner corner fully 3 times us long as that of the outer, and only slightly shorter than the outer mediate one; dorsal bristle unusually slender. Anterior antenna? much elongated, reaching, when reflexed, even somewhat beyond the 3rd segment, and clothed with rather slender setae, lateral ribs of outer joints very slight and quite simple. Posterior antennse with the terminal joint less narrow than in M. obsoletus, and scarcely longer than the penultimate one. Both pairs of maxillipeds largely developed, the anterior ones without any crenulation of the hind edge. Natatory legs with the rami very slender; apical spine of outer ramus in 2nd to 4th pairs much elongated and coarsely denticulated; terminal joint of inner ramus shorter than the other 2 combined; apical spines of this ranius in 4th pair very unequal, the outer one being extremely small, the inner very much elongated and generally somewhat bent inwards ; connecting lamella of same pair with the projections of the hind edge obtuse at the tip. Last pair of legs resembling in shape those in M. ol/.soletus, but having the apical seta? comparatively shorter. Ovisacs, as a rule, small, rounded, and containing only a very limited number of ova. Seminal receptacle resembling that of the preceding species, though having the anterior lobes more obtuse and the posterior part narrower. Body highly pellucid, with a very faint yellow tinge. Length of adult female scarcely exceeding 0.90 mm. Remarks. This form is easily recognisable by its very slender and narrow body and the long spreading setae clothing the anterior antenna?, these characters, as also its habits, somewhat recalling the slender pelagic species of the marine genus Oithona. It was indeed in allusion to this resemblance that the specific name, oithaiioitli'*. was proposed by the present author. The Cyclops hyalinus of Rehberg is unquestionably this species, as is easily seen from the figure he gives of the furca. Occurrence. I have found this form not infrequently in several of our larger lakes, more rarely in small tarns. In habits it is a true limnetic form, keeping itself always freely suspended in the water, and generally near the surface. Distribution. Sweden (Lilljeborg), Germany (Schrneil), central part of Asia (G-. 0. Sars), North America (Herrick). _ 6I 35. Mesoeyelops crassus (Fischer). (PI. XXXVII). C//rlopn crassufi, Fischer, Beitrage xur Kenntniss der Cyclopiden (Fortsetzuug). Bulletin Sue. Imp. Nat. Moscou, Tome XXVI, Part 1, p. 92, PI. Ill, figs. 13-18. Syn : Ci/clops oithonoides, var. hyalina, Schmeil. Jii/alinus, Lancle, Richard, Lilljeborg (not Eehberg). Specific Characters. Female. Body rather short and stout, with the anterior division oval in form, greatest width attaining fully half the length and occurring in the middle. Last trunk-segment small, though somewhat broader than in the 2 preceding species. Tail scarcely exceeding half the length of the anterior division ; genital segment about the length of the 3 succeeding segments combined, and somewhat tapered behind. Caudal rami unusually short and thick, scarcely exceeding in length the anal segment, and somewhat divergent; seta of outer edge very small and attached not far from the apex; apical setae of mode- rate length, the inner mediate one almost as long as the tail; seta of inner corner more than 3 times as long as that of the outer, and not much shorter than the outer mediate one. Anterior antennse somewhat less slender than in the 2 pre- ceding species, reaching, when rerlexed, about to the end of the 2nd segment, lateral rib of the outer joints very slight. Posterior antennae nearly as in M. oithonoides. Maxillipeds, however, comparatively smaller. Natatory legs with the rami less slender and the apical spines shorter; those of inner ramus in 4th pair less unequal, the inner one being scarcely more than twice as long as the outer and much shorter than the terminal joint of the ramus; connecting lamella of this pair with the projections of the hind edge coarsely dentate. Last pair of legs resembling in shape those in M. oithoiionli's. though having the distal joint somewhat smaller and the apical setse comparatively shorter. Ovisacs rounded oval in form and generally containing only a limited number of ova. Seminal receptacle about as in M. oithonoides. Body very pellucid, with a faint yellowish tinge. Length of adult female about 0.80 mm. jRemarJcs.--The identity of the above-described form with Fischer's Cyclops crassus seems to me evident. It has erroneously been identified by Dr. Schmeil and several other authors with (,'. hi/alinn* Rehberg, which, as stated above, is unquestionably a typical M. oithonoides. From the latter species it is at once distinguished by its much shorter and stouter body, and by the unu- sually short and thick caudal rami, thus fully deserving the specific name pro- posed for it by Fischer. In these respects it much more resembles the African species, M. neyiectus G. 0. Sars, which however differs in the much shorter innermost caudal seta. 62 Occurrence. I have met with this species not unfrequently in the lake Vansj0 near Moss, where it lives as a true limnetic form. I have also found it occasionally in wide expanses of the river Glommen, at Nipen. Distribution. Sweden (Lilljeborg), Germany (Schmeil), Poland (Lande), France (Richard), Russia (Fischer), Cape of Good Hope (G. 0. Sars). 36. Mesocyelops Dybowskyi (Lande). (PI. XXXVIII). Cyclops Dijboicskyi, A. Lande, Materyaly do Fauny Scorupiakow Widlonogish, Copepoda. p. 57, PI. XVII, figs. 5159. Syn: Ci/clops crassus, Lilljeborg (not Fischer). Specific Characters. Female. Body somewhat less robust than in M. crassus, with the anterior division regularly oval in outline, greatest width about half the length and occurring somewhat in front of the middle. Last trunk- segment about as in the preceding species. Tail considerably exceeding half the length of the anterior division ; genital segment about the length of the 3 suc- ceeding ones combined, and gradually tapered behind. Caudal rami more pro- duced than in M. crassus, considerably exceeding in length the anal segment, and only slightly divergent; seta of outer edge comparatively small and attached at a short distance from the end; apical setae not much elongated, the inner mediate one not nearly attaining the length of the tail; seta of inner corner much shorter than in the 3 preceding species, being only slightly longer than that of the outer corner and scarcely half as long as the outer mediate one, dorsal bristle not particularly slender. Anterior antennae of moderate length, reaching, when reflexed, about to the end of the 2nd segment. Posterior antennae and maxillipeds about as in M. crassus. Natatory legs also on the whole rather similar; apical spines of inner ramus in 4th pair, however, distinctly different, the outer spine being considerably larger than the inner. Last pair of legs with the distal joint comparatively thicker than in the other species and having the apical setse rather short. Ovisacs of moderate size, oval in shape, and rather divergent. Seminal receptacle with the anterior lobes distinctly recurved. Sper- matophores attached to the genital opening narrow oblong in form and diverging obliquely behind. Colour rather peculiar, the body being, as a rule, tinged with a dark bluish or brownish violet hue. Length of adult female about 0.90 mm. Remarks. This form, first described by A. Lande under the above specific name, has been erroneously identified by Lilljeborg with Cyclops crassus 63 Fischer, which, as stated above, is the form described by him as C. hyc&inus. Though nearly allied to that species, it may easily be distinguished by the somewhat different shape of the caudal rami, and more particularly by the comparatively short innermost apical seta. In the living state it is moreover at once recognised by the peculiar colour of the body. Occurrence. I have met with this form only quite occasionally in some small lagunes at the border of the lake 0stensj0 near Christiania, and also in wide expanses of the river Glommen, at Nipen. Distribution. Sweden (Lilljeborg). Germany (Schmeil), Poland (Lande). 37. Mesoeyelops gracilis (Lilljeborg). (n. xxxix). < 'yclops gracilis. Lilljeborg', De crustaceis ex ordinibus trilms in Scania occurrentibus, Appendix, p. 208. Specific Characters. Female. Body very slender, resembling in outward appearance that of M. oithonoides, the anterior division being narrow oblong in outline and contracted behind, with the greatest width quite in front. Last trunk- segment very small, with the lateral parts rounded off. Tail slender, equalling in length about 2 /s of the anterior division ; genital segment attaining the length of the 3 remaining segments combined, and slightly tapered behind. Caudal rami somewhat longer than the anal segment and slightly divergent; seta of outer edge attached in the middle; apical setae comparatively short, the inner mediate one scarcely exceeding half the length of the tail; seta of inner corner only slightly longer than that of the outer, and scarcely half as long as the outer mediate one; dorsal bristle of moderate length. Anterior antennae long and slender, reaching, when reflexed, to about the middle of the 3rd segment, and composed of only 11 joints clothed with very long, diverging, partly ciliated setse. Posterior antennae likewise comparatively slender, with the terminal joint longer than the penultimate one, lateral bristles of the latter joint reduced in number. Maxillipeds rather fully developed resembling in structure those in the other species of the present genus. Natatory legs, on the other hand, imper- fectly developed, the rami in all of them being composed of only 2 joints; 1st joint of outer ramus in 4th pair without any seta inside; apical spines of inner ramus in same pair very unequal, the outer one being quite rudimentary, the inner long and slender. Last pair of legs likewise imperfectly developed, the proximal joint being quite confluent with the segment, distal joint extremely small, rod-like, and carrying on the tip 2 very unequal setae, the inner one being quite rudimentary. Ovisacs comparatively small and rounded oval in shape, each con- 64 taining onl) 7 a very limited number of ova. Seminal receptacle of quite a similar shape to that in the other species of the present genus, the anterior part being bilobular, the posterior greatly produced tongue-shaped. Colour, according to Lilljeborg, dark brownish, or light greyish brown. Length of adult female about 0.80 mm. Remarks. Through the kindness of Prof. Wiren of the Upsala University I have had the opportunity of examining this interesting species, and have thereby found my above-indicated suggestion about the systematic position of this form fully confirmed. In spite of the reduction of the number of joints in the anterior antennae and the imperfect development of the legs, it must, in reality, be referred to the present genus, with which it otherwise agrees perfectly. Its resemblance, indeed, both as regards size and general appearance, to one of the above-described species, vix., M. oithonoides, is so perplexing, that at first sight it might even easily be confounded with that form. It will be found that the above- mentioned differences in the structure of the anterior antennae and the legs are quite analogous to those observed in certain species of the genus Cyclops (sens, strict.), and are merely due to a retarded development of these appendages. Occurrence. This form, it is true, has not yet been observed within the limits of our country ; but, as it occurs in the neighbouring parts of Sweden, it is very probable that, on a closer investigation, it will in reality be found in some place or other in the south-eastern part of the country. Distribution. Sweden (Lilljeborg), Germany (Schmeil), Poland (Lande). Gen. Paehyeyelops, G-. o. Sars, n. Generic Characters. Body robust, with the anterior division much dilated and boldly vaulted above. Epimeral parts of the trunk-segments not produced laterally; last segment very small. Tail not very slender, with the genital segment of moderate size and only slightly dilated in front. Caudal rami com- paratively short, but with the apical setse well developed. Anterior antennae long and slender, 17-articulate. Posterior antennae likewise slender, with long curved apical seta?. Maxillipeds comparatively shorter and stouter than in Mesocyclops. Natatory legs normally developed, with both rami 3-articulate, terminal joint of outer ramus in 1st to 3rd pairs with 3 spines outside, in 4th pair with only 2 such spines, inner edge of this joint carrying in 1st pair 3, in the succeeding pairs 4 seta;. Last pair of legs Inarticulate, proximal joint more or less pro- 65 longed and carrying at the outer distal corner the usual slender bristle, distal joint short, lamelliform, constricted at the base and trilobate at the end, carrying 2 unequal spines and an intermediate slender seta attached to a conical prominence of the joint. Seminal receptacle with the posterior part more or less distinctly bipartite. Remarks. This genus answers to the "' fuscus-albidus group'' of Dr. Schmeil, and comprises a limited number of species, which are all distinguished by their robust body, the tumid and boldly vaulted anterior division, and the very slender and elongated anterior antennae. Of anatomical details may be particularly mentioned the characteristic structure of the last pair of legs, which is very unlike that in any of the other known groups of Cyclopses. 3 species belonging to this genus will be described below, and I am inclined to believe, that also the North-American species, Cyclops ater Herrick, may be referable to this genus, though the last pair of legs are said to be uniarticulate. 38. Pachycyclops signatus (Koch). (PI. XL). Cyclops signatus, Koch, 1. c. Heft 21, Tab. 8. Syn: Cyclops qradricornis fuscus, Jurine. coronatus, Claus. fuscus, Schmeil. Specific Characters. Female: Anterior division of body broadly ovate in outline, greatest width about equalling half the length and occurring in front of the middle. Cephalic segment large and tumid, with the frontal edge narrowly truncated. Last trunk-segment very small and sharply defined from the preceding one. Tail comparatively short, scarcely attaining half the length of the anterior division ; genital segment about the length of the 3 succeeding segments combined, and almost cylindrical in form. Caudal rami rather short, though somewhat longer than the anal segment, and slightly divergent, inner edge finely ciliated; seta of outer edge very small and attached close to the end; apical setae densely plumose and rather spreading, the inner mediate one exceeding the tail in length; seta of outer corner rather elongate, though shorter than that of the inner corner. Anterior antennae very slender and attenuated, reaching, when refiexed, to the end of the 3rd segment, distal edge of the 8th, 9th, llth, 12th and 13th joints distinctly denticulated, the 3 outermost joints very narrow and exhibiting along the upper face a delicate hyaline rib, which on the proximal part of the last joint is divided into 8 strong serrations. Posterior antenna; unusually slender, with the penultimate joint long and narrow, attaining fully the length of the 9 Crustacea. 66 terminal one, antepenultimate joint comparatively short and broad, oval in form, and coarsely denticulated on the hind edge; 2 of the apical setse much more elongated than the others. Anterior maxillipeds strongly built, with the claw and spines issuing from the distal part very coarse and denticulated inside. Posterior maxillipeds, on the other hand, comparatively slender, with the first 2 joints narrower than usual. Natatory legs exhibiting the structure characteristic of the genus, rami comparatively slender, especially those of 4th pair; apical spines of inner ramus in this pair rather unequal, the outer one being much the larger. Last pair of legs with the proximal joint oblong quadrangular in form, and densely clothed inside with small spikes, distal joint somewhat shorter and much narrower, spine of inner edge almost twice as long as that of the outer, both being com- paratively slender and finely denticulated; apical seta still longer and clothed with scattered cilia. Ovisacs comparatively large and borne closely appressed to the body, so as partly to obtect the dorsal face of the tail. Seminal receptacle with the posterior part rather piodnced and narrowly cleft in the middle. Body of a more or less dark fuscous colour, with a greenish or bluish tinge and variegated with still darker irregular shadows; caudal rami and ad- joining part of tail bluish green, and also the anterior antennae and the legs tinged with the same colour, ova in the ovisacs generally of a very dark brown hue. Length of adult female amounting to 2.50 mm. Remark*. -This is one of our largest and most beautiful Cyclopids, being easily recognisable from most other species. The Cyplop* qvadricornis fuscii* of Jurine is in all probability referable to the present species ; but, as noted before, I find it scarcely admissible to appropriate the varietal names appended by that author to his species C. qvadricornis as true specific designations. That the ( 'i/plojis siynatus of Koch is this species, is quite certain, and this has also been admitted by all authors. The name C. corona tus proposed by Clans for this species is of much later date, and must of course cede to that of Koch. Occanr-nce. I have met with this handsome species chiefly at the borders of large lakes or in lagunes and ponds left by the reflux of the water in these lakes. In habits, like the other species of the present genus, it is a true bottom- torm, being frequently seen clinging to some object on the ground or to the plants growing upon it. When disturbed it darts away with a sudden bound, and so rapidly that it becomes a matter of great difficulty to catch it by the aid of an ordinary dipping-tube. Distribution. Sweden (Lilljeborg), British Isles (Brady), Germany (Schmeil), Poland (Lancle), France (Richard), Central Asia (G. 0. Sars), North America (Herrick). 67 39. Pachycyclops bistriatus (Koch). (PI. XLI). Cyclops bistriatus, Koch, 1. c. Heft 21, Tab. 7. Syn : Cyclops distinctus, Richard. gracilicornis, Lande. Specific Characters. Female. Anterior division of body regularly oval in outline, greatest width somewhat exceeding half the length and occurring about in the middle. Tail comparatively short, scarcely attaining half the length of the anterior division ; genital segment somewhat shorter and broader than in P. sig- natus. Caudal rami a little more produced, though scarcely attaining the length of the last 2 segments combined; apical setae rather spreading and exhibiting nearly the same mutual relation in length as in the preceding species. Anterior antennas still more slender and elongated than in that species, reaching, when reflexed, even to the end of the 4th segment, lateral rib of the outer joints incon- spicuous. Posterior antennse of normal structure, the penultimate joint being much shorter than the terminal one and also distinctly thicker ; apical setae, as usual, gradually increasing in length inwards. Both pairs of maxillipeds conspicuously smaller than in the preceding species. Natatory legs with the rami compara- tively broader; terminal joint of inner ramus in 4th pair somewhat curved in the middle, and having the apical spines less unequal, the inner one conspicuously bent inwards. Last pair of legs resembling in structure those in the preceding species, though having the distal joint comparatively larger in proportion to the proximal one. Ovisacs rather large and slightly divergent. Seminal receptacle with the posterior psrrt rather produced and very conspicuously bipartite. Body of a dark blue colour, with the anterior part of the cephalic seg- ment somewhat lighter. Length of adult female about 2.20 mm. Remarks. I think I am right in identifying the above-described form with Cyclops bistriatus of Koch. The figure given by Koch applies fairly well to the present form, and also his notes about the colour agree. In any case it is evident that the figure represents a true Pachycyclops, and as the 2 other species are both very recognisably figured by that author, the said figure cannot refer to any other species than the one here under discussion. As Koch's name has the precedence both to that given to the species by Dr. Richard, and to that proposed by A. Lande, it ought to be retained for the present species, though it is somewhat inappropriate, being apparently derived from the anteriorly some- what divergent dark ovarial tubes shining through the body. Dr. Schmeil at first opined that this form was merely a hybrid between th.e 2 other species; but he has subsequently recognised its specific distinctness. As to its relation to the 2 other species, I think that it comes nearer to P. signatus than to P. annulicornis. Occurrence. The only place where I have as yet met with this form, is in a small tarn near Christiansand. It occurred here, together with other Ento- mostraca, near the bank on a muddy bottom covered with coarse gravel. All the specimens observed were of a very dark bluish colour and in their whole behaviour exhibited so great a resemblance to P. siynatus, that at that time I regarded them as merely belonging to a variety of that species, for which reason I only made a coloured drawing of one of them, omitting to preserve the speci- mens for further examination. The h'gures here given are from Swedish speci- mens kindly sent to me by Prof. Wiren of the Upsala University. Distribution. Sweden (Lilljeborg), Germany (Schmeil), France (Richard), Poland (Lande). 40. Paehyeyelops annulieornis (Koch). (PI. XLII). Cijdops annulicornis, Koch, 1. c. Heft, 21, Tab. 6. Syn : Cyclops qvadricornis albidus, Jurine. ,. ,. tenuicornis. Claus. nlbidtts, Schmeil. Forbes. Specific Characters. Female. Anterior division of body broadly oval in outline, greatest width exceeding halt' the length and occurring somewhat in front of the middle. Tail comparatively more slender than in the 2 preceding species, somewhat exceeding half the length of the anterior division; genital segment of about the same shape as in P. siynatus. Caudal rami comparatively short and only slightly diverging, inner edge scarcely ciliated; apical setse less densely plumose and less spreading than in the 2 preceding species, the inner mediate one almost attaining half the length of the body; seta of outer corner comparatively short, scarcely exceeding in length */ 3 of that of the inner corner. Anterior antennae long and slender, reaching, when reflexed, beyond the 3rd segment, outer joints very narrow and exhibiting a well-defined lateral rib, which is quite smooth through- out, and projects at the end in a small lappet. Posterior antenna? with the terminal joint much longer and narrower than the penultimate one. Maxillipeds about as in P. biatrintu.s. Natatory legs likewise very similar; terminal joint of inner ramus in 4th pair, however, distinguished by the quite rudimentary con- dition of the distal seta of inner edge; apical spines of this ramus slightly une- qual, the outer one being the larger. Last pair of legs of almost exactly the same shape as in P. xiyiKi.ktis. the distal joint being conspicuously smaller than the 69 proximal one. Ovisacs generally narrow oblong or fusiform in shape and, as a rule, diverging greatly, in some cases, however, more appressed to the body. Seminal receptacle with the posterior part very little produced and slightly emarg- inated in the middle. Spermatophores attached to the genital orifice lageniform and closely juxtaposed. Body of a clear yellowish grey colour, with a more or less distinct olivaceous tinge, and variegated with dark transverse bands at the end of some of the segments, as also across the cephalic part; anterior antennae generally with 2 very conspicuous dark bands, the one occupying the 2nd and 3rd joints, the other the 10th and llth joints. Length of adult female about 1.80 mm. Remarks. This form has generally been recorded by recent authors under the name of Cyclops albidus .Turine, a name which is very little significant, as the present species in most cases exhibits a rather conspicuous colouring of the body. For the reason noted above the name ought also to be rejected, and to be replaced by that proposed by Koch, which has the precedence to the name tenuicornis given to the species by Glaus. The Cyclops i/t/rhittx of Forbes is unquestionably this species, and is not, as opined by Dr. Schmeil, identical with C. distinetus Richard. The present species is nearly allied to the 2 preceding ones, but is of smaller size, and moreover easily recognisable from them by the shortness of the outermost caudal seta. The manner in which the ovisacs are born is also very characteristic, though in some cases specimens are found in which they are more appressed to the body, a circumstance which at first led me to the erro- neous opinion that these specimens might belong to a different species. Occurrence. This is one of our commonest Cyclopids, being found both in small ponds and ditches and in large lakes. In the latter it not only occurs at the borders, but descends to rather considerable depths. In the lake Mjosen I have even taken it in great numbers down to 50 fathoms together with Cyclops vulgaris. Distribution. Throughout Europe, northern part of Asia, Central Africa, Australia, North and South America, Hawaii Islands. The distribution of this form is accordingly almost cosmopolitan. 70 Gen. 15. LeptOCydOpS, (i. O. Sars, n. Generic Character*. Body more or less slender, with the 2 chief divisions very sharply defined. Epiraeral parts of the trunk-segments, as a rule, distinctly prominent laterally, especially those of penultimate segment, though rounded at the extremities. Last trunk-segment short and broad, being produced on each side to a narrowly rounded and densely hairy lobe, somewhat impinging upon the base of the genital segment. Tail very slender and narrow, with the genital segment comparatively short and abruptly contracted immediately behind the base. Caudal rami more or less prolonged, and in most cases exhibiting along the outer edge a delicate denticulation ; seta of this edge small and not far from the end; middle apical seta? slender and elongated, being, as a rule, clothed on the proximal part with scattered coarse hairs; seta of inner corner of incon- siderable length and very thin, that of the outer corner more or less spiniform. Anterior antennae in all the known species composed of 12 joints, the outer ones generally very slender and narrow. Posterior antennae and oral parts on the whole of normal structure. Natatory legs well developed, with 3-articulate rami; 1st pair, as usual, the smallest, and having the 2nd basal joint conically pro- duced at the inner corner and provided with a long deflexed spine ; armature of the rami as in the genus Pachy Cyclops. Last pair of legs very small, each forming a simple somewhat trilobate lamella armed inside with a denticulated spine, outside and at the conically exserted tip with a slender seta. Ovisacs generally oval fusiform in shape. Seminal receptacle with the posterior part not produced, forming 2 transverse bands defined in the middle by a slight emargination. Remarks. The type of this genus is the species generally described under the name of Cyclops serrttlutus Fischer, with which Dr. Schmeil has con- nected another rather diviating form, C. /trn.^nui^ Fischer, to form a particular group of Cyclopses, viz.. his "serrulatus-prasinus group". The most prominent character distinguishing this genus from the 3 preceding ones, is undoubtedly the very different structure of the last pair of legs. Several other characters common to the greater number of the species comprised within this genus may also be adduced, and are shortly enumerated in the above diagnosis. The genus seems to be very rich in species; but most of these are so closely related to each other, that they can be distinguished only by a careful examination, and for this reason they have been regarded by most earlier authors as only varieties of one and the same species, viz., C. serrulatus of Fischer. In the following 71 pages 5 Norwegian species belonging to this genus will be described. To these may be added a considerable number of exotic species. I have for instance recorded no less than 7 species from the Central African lake, Tanganyika, and another well-defined African species is known to me from Cape Colony. Moreover the North-American species, Cyclops I'lcyaiis Herrick and 6'. pectinifer Cragin, unquestionably belong to the same genus, and also 2 other, apparently new species from the same part of the world have been examined by me. 41. Leptocyclops agilis, (Koch). (PI. XLIII). Cyclops ayilifi, Koch, 1. c. Heft 21, Tab. 3. Syn : Cyclops fterrnlatus. Fischer. rarius, var. brachytvra, Lilljeborg. Specific Characters. Female. Body moderately slender, with the anterior division oval in outline, greatest width somewhat exceeding half the length and occurring in the middle. Tail slender, about equalling in length -j- A of the anterior division; genital segment scarcely longer than the 2 succeeding segments com- bined and considerably dilated at the base. Caudal rami generally not much prolonged, equalling about the length of the last 2 segments combined, and slightly bent outwards at the ends, outer edge finely denticulated throughout; seta of this edge very small and attached near the end somewhat dorsally ; middle apical setse rather slender and, as usual, clothed in their proximal parts with scattered coarse hairs, the inner one about equalling half the length of the body, the outer considerably shorter; seta of inner corner scarcely longer than that of the outer, which is much coarser, spiniform. Anterior antennae long and slender, reaching, when reflexed, to the end of the 2nd segment, the 3 outer joints very narrow and bordered by a hyaline rib, which is quite smooth through- out. Posterior antennae with the terminal joint scarcely longer than the penulti- mate one. Anterior maxillipeds comparatively short and stout, with the sub- division of the 1st basal segment indistinct. Posterior maxillipeds likewise short, with the outer 2 joints imperfectly defined and the setse issuing from them in front stout and curved against each other. Natatory legs exhibiting the structure characteristic of the genus; apical spines of inner ramus in 4th pair of moderate size, the inner one somewhat longer and more slender than the outer. Last pair of legs with the spine of the inner edge very large and coarsely dentate. Ovisacs oval fusiform in shape and slightly divergent, each containing a rather limited number of ova. Seminal receptacle with the anterior part transversely elliptical in form and slightly emarginated anteriorly. _ 72 Colour more or less dark olivaceous, with a greenish tinge ; genital segment and bases of the caudal rami generally ochraceous. Length !of adult female scarcely exceeding I mm. Remarks. This appears to be the species that has been observed by most authors, and to which the name Cyclops serrulatus Fischer has generally been applied. It seems evident to me, indeed, that the figures given by Fischer are referable to the present species; but, as the name agUix proposed by Koch is of much earlier date, it must be retained for the species. Lilljeborg has applied the name semdattt* to a different species, which will he described below as L. Lilljeborgi, whereas he has given to the present species a new name, viz., Cyclojt* rai'iu*. The latter species he again divides into 3 varieties, viz., C. speratus, C. proct-imitx and C. Iraclii/nrus. The first of these supposed varieties I regard as a distinct species, whereas the other 2 must be combined within the species here under consideration. The C. pi'o.nmus does not differ from the typical form (C. brachyurus) except in the somewhat longer caudal rami. Occurrence. This is a very common Cyclopid, being found everywhere in small ponds and ditches, as also at the margin of large lakes. It is a very active little creature, moving about with considerable speed, and thus fully deserving the specific name given to it by Koch. Like the other species of the present genus, it is however a true bottom-form, keeping constantly near the ground, and scarcely ever being met with in company with the true lim- netic species. Distribution. Throughout Europe, central and northern parts of Asia. Algeria, Azores, Polar island north of Grinnell Land (2nd Fram Exped.), North America, Australia. 42. Leptocyelops speratus, (Lilljeborg). (PI. XLIV). Ct/rlojix rftriitH, var. speratn, Liljeborg, Synopsis speciernm generis Cyclops, p. 88, PI. V, figs. 1215. Specific Characters. Female. Rather like the preceding species, but of much larger size and somewhat more slender form of body. Caudal rami considerably prolonged, attaining almost the length of the last 3 segments com- bined, and closely approximate throughout, not being at all divergent, outer edge nearly smooth, or with only very slight traces of denticles in its posterior part; middle apical setse of the usual structure, seta of inner corner considerably longer than the spine of the outer. Anterior antennae very slender, reaching, when reflexed, even beyond the 2nd segment, outer joints with a distinct 73 lateral rib, which, as in the preceding species, is quite smooth. Posterior antennne and anterior maxillipeds about as in that species. Posterior maxillipeds with the last 2 joints well defined. Natatory legs comparatively more strongly built than in the type species, with the rami broader; apical spines of inner ramus in 4th pair rather strong, the inner one being the longer. Last pair of legs somewhat more produced in relation to the width, and having the spine of the inner edge still larger, with very coarse denticles on both edges. Ovisacs comparatively large and considerably divergent. Seminal receptacle with the anterior part evenly convex in front. Colour light olivaceous or yellowish grey. Length of adult female 1.20 to 1.50 mm. Remarks. This form, as stated above, was considered by Lilljeborg as merely a variety of his species Cydops variiis (= C. agilis Koch). I think, how- ever that it is entitled to be ranged as a distinct species, as it differs not only in its much larger size, but also in some structural details mentioned in the above diagnosis. Occurrence. I have hitherto only met with this form in 2 localities, viz., in some small lagunes at the border of the lake 0stensj0, near Christiania, and in widenings of the river Glommen. at Nipen. In both localities it only occurred quite occasionally. Distribution. Sweden (Lilljeborg). 43. Leptoeyclops Lilljeborgi, G. 0. Sars, new name. (PI. XLV). Cyclops serrulatus, Lilljeborg, Synopsis, p. 81, PI. V, figs. 1 6 (not Fischer). Specific Characters. Femnl<'. Body somewhat less slender than in the last-described species, and more resembling in shape that of L. agilis. Caudal rami, however, more produced, nearly attaining the length of the last 3 segments combined, and slightly flexuous, with the distal part somewhat divergent; outer edge distinctly denticulated throughout, the denticles being especially conspicuous in the distal part; middle apical setse of the usual structure; seta of inner corner unusually prolonged, attaining almost the length of the corresponding ramus; spine of outer corner likewise somewhat longer than usual, though much shorter than the said seta. Anterior antennae long and slender, reaching, when reflexed, to the end of the 2nd segment, lateral rib of the outer joints well marked and on the proximal part of last joint divided into a number of well-marked denticles, otherwise only very faintly striated. Posterior antennae and oral parts of normal 10 Crustacea. structure. Natatory legs likewise much as in the preceding species, though having the apical spines of the rarai more coarsely denticulate; those of inner ramus in 4th pair very unequal, the inner one being nearly twice as long as the outer. Last pair of legs with the spine of the inner edge much feebler than in the 2 preceding species, and only minutely denticulated. Ovisacs of moderate size and somewhat divergent. Seminal receptacle with the anterior part very broad, occupying almost the whole width of the genital segment, and having the front edge nearly straight. Colour olivaceous, with a more or less brownish tinge. Length of adult female only slightly exceeding 1 mm. Remarks. This form was identified by Lilljeborg with Cyclops serru- /nlitx of Fischer, chiefly on account of a short note given by that author, according to which, on a strong amplification, irregular rows of very small spinules were traced on the outer joints of the anterior antennae. As however similar spinulos are also stated to occur on the tail and on the trunk segments, it seems to me very questionable whether this structure in reality refers to the dentate portion of the lateral rib, as opined by Lilljeborg. In any case the figures given by Fischer are evidently not referable to the present species but to C. ayilis Koch. Through the kindness of Prof. Wiren of the Upsala University, I have had the opportunity of examining the type specimens from which Lilljeborg's description was made. Occurrence. I have found this form occasionally in several places near Christiania, sometimes in small tarns, sometimes in ponds and ditches. In a sample taken in France by Dr. Sig. Thor, and kindly sent to me for examination, this form occurred not unfrequently together with L. ayilis, and could at once be distinguished from the latter by the rather different shape of the caudal rami. Distribution. Sweden (Lilljeborg), France (G. 0. Sars); very probably also distributed in other parts of Europe. 44. Leptocyclops maeruroides, (Lilljeborg). (PL XLVI). < '//clops macruroideSj Lilli'eborg, Synopsis, p. 85, PI. V, figs. 7 11. Specific Characters. Female. Body somewhat more slender than in the last described species, with the tail comparatively longer in proportion to the anterior division. Caudal rami very narrow and prolonged, exceeding somewhat in length the last 3 segments combined, and diverging very little, though some- what remote at the base; outer edge distinctly denticulate throughout, seta of that edge somewhat remote from the end ; middle apical seise of the usual 75 appearance; seta of inner corner scarcely more than half as long as the corre- sponding ramus, though longer than the spine of the outer corner; the latter comparatively short and thick. Anterior antenna? less elongated than in the preceding species, scarcely reaching, when reflexed, beyond the middle of the 2nd segment, lateral rib of the outer joints very finely denticulated in the proximal part of last joint, otherwise quite smooth. Posterior antenna? and oral parts scarcely different in structure from these parts in the preceding species. Nata- tory legs rather strongly built, but likewise of the usual structure. Last pair of legs with the spine of the inner edge comparatively shorter than in L. Lilljeliori/i. but much thicker and coarsely denticulated. Ovisacs rather large and somewhat divergent. Seminal receptacle with the anterior part less broad than in the last described species. Colour light yellowish grey. Length of adult female amounting to 1.30 mm. Remarks. This species is nearly allied to L. LUljeborgi, but may be easily distinguished by the very narrow and prolonged caudal rami and by the somewhat shorter anterior antennae. It also grows to a considerably larger size than that species. The North American form, Cyclops elegans Herrich, of which I have had specimens for examination, is not. as opined by Lilljeborg, identical with the present species, as it has the anterior antennae much more elongated and also exhibits some differences in the structure of the caudal rami and of the last pair of legs. Occurrence. I have only met with this species in large lakes, for instance, in the Maridal Lake near Christiania, and in the great lakes Mj0sen and Tyrifjord. It is generally found at a depth of a few fathoms, near the margin, but in some cases it descends to much greater depths. In Lake Mj0sen I have for instance taken it occasionally down to 50 fathoms. Distribution. Sweden (Lilljeborg), peninsula of Kola and northern part of Siberia (same author). 45. Leptoeyelops macrurus, G. 0. Sars. (PI. XLVII). Cyclops macrurus, G. 0. Sars, 1. c. p. 45. Syii: Cyclops maarensis, Vosseler. Specific Characters. Female. Body rather slender, with the tail much produced and only slightly shorter than the anterior division. Caudal rami ex- ceedingly long and narrow, almost attaining the length of the whole remaining 76 part of the tail, linear in shape and scarcely at all divergent; outer edge for the greater part of its extent quite smooth, with only a short, somewhat oblique row of 4 or 5 small denticles just in front of the seta of this edge; the latter rather remote from the end, and attached somewhat dorsally; middle apical setae of the usual structure ; seta of inner corner fully twice as long as the spine of the outer. Anterior antennae much shorter than in any of the preceding species, scarcely reaching, when reflexed, to the end of the cephalic segment, outer joints less narrow and without any distinct lateral rib. Posterior antennae and oral parts of the usual structure. Natatory legs likewise built in the usual manner; apical spines of inner ramus in 4th pair rather strong and coarsely denticulate, the inner one only slightly longer than the outer. Last pair of legs with the spine of the inner edge very small. Ovisacs of smaller size than in the other species and closely appressed to the tail. Seminal receptacle with the anterior part narrowly exserted on each side. Colour light yellowish grey, with a faint olivaceous tinge. Length of adult female amounting to 1.10 mm. Remarks. This species was established by the present author as early as the year 1863, and has been admitted by all subsequent authors. It is indeed easily distinguishable by its extremely long and narrow caudal rami, which give to the tail a more slender appearance than in most other Cyclopidae, a character which has given rise to the specific name proposed. According to Dr. Schmeil, the Cyclops maarensis of Vosseler is identical with the present species. Occurrence. Like the last described species, this form chiefly belongs to the fauna of large lakes, occurring there in shallow water among aquatic plants. It is also occasionally found in small lagunes and ponds formed by the reflux of the water in these lakes. Distribution. Sweden (Lilljeborg), British Isles (Brady), Germany (Schmeil), Poland (Lande), France (Richard). Gen. 16. PlatyeyClOpS, G. 0. Sars, n. Generic Characters. Body comparatively robust, with the anterior part conspicuously applanated and the epimeral parts expanded laterally. Last trunk- segment short and broad, with the lateral parts more or less densely hairy. Tail robust, sub-cylindric in shape, and having the genital segment comparatively short and stout. Caudal rami of different shape in the different species, and 77 generally clothed on the dorsal face with oblique rows of tine spikes; middle apical setse comparatively strong and rather unequal in length, being minutely denticulated for a good part of their length. Anterior antennae short, with the number of joints more or less reduced. Posterior antennae likewise less slender than in the preceding genera. Both pairs of maxillipeds comparatively short and stout; the posterior ones with the outer 2 joints confluent. Natatory legs with the basal part broad and flattened, the rami 3-articulate and nearly equal in length ; middle joint of inner ramus in 1st pair with only a single seta inside ; terminal joint of same ramus in all the pairs comparatively small. Last pair of legs in some cases well defined, each forming a small lamella carrying 2 thin setae and inside them a denticulated spine, in other cases replaced on each side by 3 spines only. Seminal receptacle short and broad, not produced behind. Remarks. The present genus answers to the last of the groups of Cyclopses distinguished by Dr. Schuieil, viz., his "phaleratus affinis fimbriatus group". The species belonging to this genus are especially distinguished by the pronouncedly applanated form of the anterior division of the body, which gives them a rather characteristic appearance, and also exerts a certain influence on the movements of the animal. It is indeed from this character that the generic name here proposed has been derived. In some particulars a certain agreement with the preceding genus Leptocyclop* may be found to exist; but in other points the species here under consideration differ so much, that they cannot properly be brought together in the same genus. In addition to the 3 Norwegian species described below, the Cyclops Poppe'i Rehberg is unquestionably referable to the present genus. This form, it is true, has been considered by Dr. Schmeil as merely a variety of (,'. fimbriatus Fischer; but in. my opinion it ought to be kept apart as a distinct, though nearly allied species. Further, among the several species of Cyclops recorded by the present author from Lake Tanganyika, the 2 forms, C. oligarthrus and C. comport ti* are undoubtedly members of the same genus. We know accordingly as yet of 6 different species belonging to the present genus. 78 46. Platyeyelops phaleratus, (Koch). (PI. XLVIII) Cyclops phdleratus, Koch. 1. <., Heft 21, Tab. 9. Syn: Cyclops cantliocarpoides, Fischer. Ictficinis, Poggenpol. Specific Characters. Female. Body rather short and stout, with the anterior division pronouncedly applanated and broadly oval in outline, greatest width about equalling - ;3 of the length and occurring in the middle. Cephalic segment of moderate size, about the length of the 4 succeeding segments com- bined, and evenly rounded in front. Last trunk-segment comparatively broad, with the lateral parts slightly produced and minutely hairy. Tail unusually robust, somewhat exceeding half the length of the anterior division, and having the posterior edge of all the segments coarsely denticulated ventrally and later- ally; genital segment scarcely as long as the 2 succeeding segments combined, and of nearly equal width throughout; last segment very short. Caudal rami short and thick, about equalling in length the penultimate segment, and scarcely diver- gent, distal part a little contracted and obliquely truncated at the end, upper face crossed by 3 obliquely curved rows of very delicate spikes, outer edge clothed in the middle with a few small spinules, seta of this edge very small and not far from the end. issuing somewhat dorsally; middle apical setse very strong and clothed for the greater part of their extent with small appressed spinules, the inner one more than twice as long as the outer; seta of inner corner small, scarcely longer than the spine of the outer. Anterior antennae much shorter than the cephalic segment and only slightly dilated in their proximal part, being composed of 10 joints clothed with comparatively short simple setae; 1st and 6th joints the largest. Posterior antennae very strongly built, with the first 2 joints imperfectly defined, 3rd joint densely hairy in front and on the upper face, its seta very short, spiniform; terminal joint much shorter than the penultimate one, apical seta? of both joints very coarse and curved. Mandibles and maxillae of usual structure. Anterior maxillipeds very short and stout, with the basal part much dilated. Posterior maxillipeds likewise unusually stout, with the first 2 joints imperfectly defined, the 2nd exhibiting outside a ledge densely clothed with spinules, last joint very small and conically produced inside, carrying 2 short, thick, hairy seta? and outside them 2 thin bristles. Nata- tory legs distinguished by their exceedingly broad basal part and the coarsely spinulose rami; 2nd basal joint in 1st pair only slightly produced at the inner corner, but having the deflexed spine of quite an unusual size; terminal joint of outer ramus in 1st 3rd pairs with 3 coarse spines outside, in 4th pair with 79 only 2 such spines; apical spine of inner ramus in 1st pair not particularly strong; those in 4th pair very unequal, the inner one more than twice as long as the outer and equalling in length the 2 outer joints of the ramus combined. Last pair of legs imperfectly developed, and replaced on each side by 3 strong- ciliated spines attached to the lateral corners of the corresponding segment, the outermost spine heing somewhat thinner and less densely ciliated than the other 2. Ovisacs of moderate size, oblong oval in form and generally closely appressed to the sides of the tail. Ovarial tubes extending backwards more or less far within the tail, generally to the penultimate segment. Seminal receptacle short and broad, occupying almost the whole width of the genital segment. Colour generally dark reddish brown, with the 1st free trunk-segment somewhat lighter. Length of adult female about 1.10 mm. Remark*. This very characteristic form was first recorded by Koch, who has given a very recognisable figure of an adult female specimen. It was subsequently redescribed by Fischer as a new species under the name C. cci'H- thocarpoides, a name that was also adopted by some of the subsequent authors. According to Dr. Schmeil, the Cyclops Irt.scini* of Poggenpol is also identical with the present species. Occurrence. I have found this form occasionally in stagnant pools near Christiania, especially in such as have their surface more or less densely covered with Lemma. Like the other species of the present genns, it is a true bottom form, keeping constantly close to the ground, along which it moves with great rapidity. Even when out of the water, it has the power for some time of creeping along a plane surface. The manner in which the male gets hold of the female during copulation, is rather different from that observed in most other Cyclopida?, and more resembles that generally found in the Harpac- ticoida. As in the latter, the male grasps the female with his prehensile anterior antennae dorsally across the tail, and the hold is so firm that it not infrequently happen that the two sexes remain tied together in this manner after being killed in alcohol. Distribution. Throughout Europe, Turkestan (H. Ganin), North America (Herrich), Australia (G. 0. Sars). 80 47. Platy eyclops af finis, G. 0. Sars. (PI. XLIX). I'l/i-lnpx affmis, G. O. Sars, 1. c.. p. 47. Syn: Cyclops pugmccm, Eehberg. Specific, Characters. Female. Body somewhat less robust than in the preceding species, with the anterior division comparatively narrower. Cephalic- segment considerably exceeding in length the 4 succeeding segments combined, and narrowly rounded in front. Last trunk-segment with the lateral parts slightly produced and clothed at the edge with slender recurved spinules. Tail about equalling in length -,.-. of the anterior division, and slightly tapered distally; genital segment about as long as the 2 succeeding segments combined, and some- what dilated at the base, last segment more fully developed than in P. phalcratii*. though smaller than the penultimate segment. Caudal rami resembling in shape those in that species, but a little more produced ; seta of outer edge very small, and attached near the end somewhat dorsally; upper face crossed by a row of small spikes extending from the said seta obliquely anteriorly ; middle apical setse strong and minutely denticulated for some part of their length, the inner one about twice as long as the outer, and equalling about half the length of the body; seta of inner corner very small, shorter than the spine of the outer. Anterior antennse shorter than the cephalic segment, and, as in the preceding species, not much dilated in their proximal part, being composed of 11 joints clothed with short, simple setse. Posterior antennae far less robust than in P. phaleratus, with all the joints well defined. Maxillipeds resembling in struc- ture those in that species ; the posterior ones, however, wanting the spinulose ledge of the middle joint. Natatory legs with the basal part less broad and the rami less coarsely spinulose outside: 2nd basal joint in 1st pair obtusely produced at the inner corner, with the detiexed spine rather slender, terminal joint of outer ramus in 1st and 2nd pairs with 3 spines outside, in 3rd and 4th pairs with only 2 such spines; apical spine of inner ramus in 1st pair rather coarse; those in 4th pairs, as in the preceding species very unequal, the inner one being more than twice as long as the outer and conspicuously bent inwards; middle joint of same ramus with only a single seta inside. Last pair of legs well defined, each forming a small sub-quadrangular lamella carrying inside a very slender denticulated spine, outside a seta of about same length, and in the middle another much smaller seta. Ovisacs comparatively smaller than in the preceding species and containing only a limited number of ova. Seminal recep- tacle less broad. Cyclopidae. Copepoda Cyclopoida. !P1. XXXIII. \ G. O. Sars, del. Cyclops varicans, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XXXIV. G. O. Sars, del. Cyclops bicolor, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. Pi. xxxv. * G. O. Sars, del. Mesocyclops obsoletus (Koch). Cyclopidse. Copepoda Cyclopoida. PL XXXVI. // G. O. Sars, del. Mesocyclops oithonoides, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XXXVII. / ! w : 1 / J - \ ' i 1 i \ // I ' ; ' ! ! ! I G. O. Sars, del. Mesocyclops crassus, (Fischer). Cyclopidse. Copepoda Cyclopoida. PI. XXXVIII. \ ' - IS \ G. O. Sars, del. Mesocyclops Dybowskyi, (Lande). Cyclopidae. Copepoda Cyclopoida. PI. xxxix. .> - *'i - ,._-!- J-y-*-*- f|p*" > \ ^ G. O. Sars. del. Mesocyclops gracilis, (Liiljeb). Cyclopidae. Copepoda Cyclopoida. PI. XL. G. O. Sars, del. Pachycyclops signatus, (Koch). Cyclopidae. Copepoda Cyclopoida. Pi. XLI. G. O. Sars, del. Pachycyclops bistriatus, (Koch). Cyclopidse. Copepoda Cyclopoida Pi. XLII. m \ nii\\ ' G. O. Sars, del. Pachycyclops annulicornis, (Koch). Cyclopidae. Copepoda Cyclopoida. PI. XLIII. * - '-T- \\ I -'V i G. O. Sars, del. Leptocyclops agilis, (Koch). Cyclopidse. Copepoda Cyclopoida. PI. XLIV. j . , G- O. Sars, del. Leptocyclops speratus, (Lilljeb). Cyclopidse. Copepoda Cyclopoida. PI. XLV. G. O. Sars, del. Leptocyclops Lilljeborgi, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PI. XLVI. , '- -- A ' r+^ *>- G. O. Sars, del. Leptocyclops macruroides, (Lilljeb). Cyclopidae. Copepoda Cyclopoida. PI. XLVII. G. O. Sars, del. Leptocyclops macrurus, G. O. Sars. Cyclopidae. Copepoda Cyclopoida. PL XLVIII. 7 // j i '/i.^. /' . . ?" ' G. O. Sars, del. Platycyclops phaleratus, (Koch). AN ACCOUNT OF THE CPOSTACEA OF NORWAY WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES BY G. O. SARS VOL. VI COPEPODA GYGLOPOIDA PARTS VII & VHI CYCLOPID^E (concluded), ASCOMYZONTID^E WITH Hi Al'TOTYPlC PLATES BERGEN PUBLISHED BY THE BERGEN MUSEUM SOLD BY ALB. CAMMERMEYER'S FORLAG, CHRISTIANIA 1915 _ 81 Colour generally dark bluish grey. Length of adult female about 0.75 mm. Remarks. In its general appearance this form somewhat resembles the preceding species, but is of much smaller size and has the body less robust. It moreover exhibits several well-marked differences in the structure of the antennae and legs, as indicated in the above diagnosis. The Cyclops pyymoeus of Rehberg is unquestionably identical with the present species. Occurrence. I have taken this form in similar localities to those in which the preceding species has been found. It also occurs occasionally at the borders of large lakes or in closed lagoons formed by the reflux of the water in these lakes during the dry season. Distribution. Throughout Europe, Turkestan (Uljanin), Australia (G.O.Sars). 48. Platycyclops fimbriatus (Fischer). (PI. L). fnnlriattis. FisHirr, I-V-itrfige zur Kenntniss der Cyclopiden (Fortsetzuiig). Bnll.Soc.ini]). Moscou 1853. p. 94, PI. Ill, figs. 1928, 30. Syn : < '//(tups crassiconits, ccific Characters. Female. Anterior division of body rather broad and expanded, with the cephalic segment very large and evenly rounded in front; lateral parts of the succeeding segments rounded off at the end. Tail compara- tively short, scarcely exceeding in length V;; of the anterior division ; genital segment moderately dilated and occupying more than half the length of the tail; anal segment scarcely longer than the preceding one. Caudal rami short, about as long as they are broad ; apical setse not much elongated. Anterior antennae nearly as long as the cephalic segment, and composed of 20 articulations, all 3 joints of the terminal part being well defined. Posterior antennas about as in A. Lilljeboryi. Oral cone, as in that species, terminating in a narrow siphonal tube, which however is considerably shorter, only extending a little beyond the 89_ insertions of the 1st pair of legs, and does not exhibit any trace of a transverse striation. Maxilloe with the inner lobe considerably produced and tapered distally, the apical setse being likewise unusually slender; outer lobe very small. Max- illipeds rather powerfully developed; claw of the anterior ones strong and much elongated, with the end evenly curved and the concave edge finely ciliated through- out. Natatory legs of normal structure. Last pair of legs nearly as in A. Lilljeborgi. Male, as usual, smaller than female, and moreover easily recognisable by the distinctly hinged anterior antennae and by the structure of the tail. Colour not yet ascertained. Length of adult female about 0.90 mm., of male 0.75 mm. Remarks. Brady erroneously considered this form to be identical with A. Lilljeborgi Thorell, and the change of the specific name was merely made to distinguish it from Asterochere* Lilljeborgi of Boeck. The species is however in reality quite distinct from both of those forms, though nearest allied to A. Lilljeborgi Thorell, from which it is distinguished by the much shorter siphon. Occurrence. A solitary female specimen of this form was taken, many years ago, at Bukken, SW coast of Norway, from some dredged material, and a few additional specimens were picked up recently from the bottom-residue of a large collecting-bottle containing a number of different invertebrate animals taken at Rau0 ; west coast of Norway. I am of course unable to decide from what hosts the specimens were derived nor is any information upon this point given by Brady. . British Isles (Brady), '? Gulf of Naples (Giesbrecht). 52. Aseomyzon simulans, Scott. (PI. LV). Asco)i///:.nn NiiiiiilfiiiN. Scott, Sixteenth Aim. Rep. of the Fisheries Board for Scotland. Part III, p. 270, PI. XIII, tigs. 19. PI. XIV, fig. 22. Specific Characters. Female. Anterior division of body less broad than in the preceding species, the greatest width being much smaller than the length. Cephalic segment of moderate size and evenly rounded in front. Lateral parts of the 2 succeeding segments obtusely rounded, those of the last 2 segments slightly angular. Tail very short, scarcely 1 / 3 the length of the anterior division ; genital segment considerably dilated, being even somewhat broader than it is long; anal segment about the length of the preceding one and somewhat con tracted behind. Caudal rami exceedingly small, being broader than they are 1-' I'nistaceu. 90 long; apical setae comparatively short. Anterior antennae not quite as long as the cephalic segment, and composed of 20 articulations, all 3 joints of the ter- minal part being well defined; proximal portion of the antennae rather thick and very sharply marked oft' from the slender distal portion. Posterior antennae com- paratively strong, with the penultimate joint somewhat shorter than the preceding one. Oral cone not much produced, pyriform, extending scarcely beyond the insertions of the posterior maxillipeds. Mandibles with the masticatory part moderately prolonged and terminating in a lancet-shaped point; palp normal. Maxillae with the inner lobe of moderate si/e and the apical setae comparatively short; outer lobe scarcely more than 1 / 3 the length of the inner, and much narrower. Maxillipeds of normal structure. Natatory legs well developed, with the rami comparatively broader than in the preceding species. Last pair of legs with the distal joint oval in form and cariying, in addition to the 2 apical setae, a small bristle attached inside the latter. Ovisacs of moderate size and oval in form. being only slightly divergent. Male differing from female in a manner similar to that in the other species. Body in both sexes rather pellucid, with a slight rosy tinge. Length of adult female about 1 mm , of male 0.72 mm. Remark*. This form was referred by Scott with some doubt to the genus Axconii/zon. It is however certainly a genuine member of this genus, as defined here, though well defined from the other species. Occurrence. I have long been aware of this form, of which several speci- mens have been collected at different times off the south coast of Norway, and always on Sponges, for which reason I had noted it with the provisional name A. spongiopliilum. It also occurred in great numbers in the bottom-residue of the same collecting-bottle from which A. Boecki was procured, and as this bottle contained, besides other invertebrate animals, also a number of sponges, it is most likely that they were in reality derived from the latter. Distribution. British Isles (Scott). 53. Aseomyzon latum, (Brady). (PI. LVI). Cijdopicera lata. Brady. Monograph of British Copepoda, Vol. III. p. 06. PI. LXXXIX. fig. 12, PI. XC. ti^s. 11 14. Syu: Asterocheres Boecki, (liesbrecht Specific Characters. Female. Anterior division of body very broad and expanded, the greatest width being almost equal to the length. Cephalic segment large, with the frontal edge narrowly rounded. Epimeral parts of 2nd segment 91 simple and not projecting at all laterally; those of 3rd (antepenultimate) segment, on the other hand, terminating in a very conspicuous prominent corner. Penulti- mate segment, as usual, much smaller than the preceding ones. Tail considerably exceeding in length l ;! of the anterior division; genital segment rather dilated in its anterior part and, like the other species, having the lateral edges clothed with stiff hairs; posterior edge of this and the succeeding segment, moreover, finely denticulate; anal segment longer than the preceding one. Caudal rami somewhat produced, being about as long as the anal segment; apical setse rather long and divergent. Anterior antennse very slender, equalling about in length the cephalic segment, and composed of 20 articulations, all 3 joints of the terminal part being well defined; proximal portion of the antennse comparatively short and very sharply marked off from the narrow distal one. Posterior an- tennse more slender than in A. slmtdans, and having the penultimate joint about as long as the preceding one. Oral cone rather produced and gradually tapered, extending about to the insertions of the 1st pair of legs. Mandibles with the masticatory part long and slender; palp normal. Maxillae resembling in structure those in A. simulans, though the seta 3 of the inner lobe are comparatively longer. Maxillipeds and natatory legs of normal structure. Last pair of legs with the distal joint oval in form, and provided with only 2 apical setse. Body pellucid, tinged in some places with light yellow. Length of adult female 0.80 mm. Remarks. I cannot doubt that the above-described form is that recorded by Brady in his Monograph as Gyclopicera lata. Brady believed this form to be identical with Norman's Ascomyzon echinicola', but the form so named in Giesbrecht's work and figured on PI. 2, II, is certainly a different species. On the other hand, it would seem that Giesbrecht has confounded the present species and A. BoecJii Brady. In any case the coloured figure given on PI. 1 is unquestionably referable to the present species and not to ^-1. Boccki. The prominent lateral corners of the antepenultimate trunk-segment will suffice for an immediate recog- nition of the present species as distinct from any of the others. Occurrence. I have occasionally met with this form at Ris0r and Grimstad, south coast of Norway, in moderate depths among algse, and a few additional specimens were picked up from the bottom residue of the same collecting- bottle in which A. Boecki and .1. ximtilans occurred. Distribution. British Isles (Brady), Gulf of Naples (Giesbrecht). 54. Ascomyzon parvum, (Giesbrecht). (PL LVII). Asterocheres parvus, uicslirecht. Fauna uml Flora cles Golfes von Neapel; 25th Monographie, Die Asterocheriden, p. 100, PI. 2, F. Specific Characters. Female. Anterior division of body less expanded than in A. latum. the greatest width not nearly attaining the length. Cephalic segment of moderate size and evenly rounded in front. Lateral parts of the trunk-segments rounded off at the end, the antepenultimate segment not differing in this respect from the others. Tail almost attaining half the length of the anterior division, and having the posterior edge of the segments perfectly smooth ; genital segment less broad at the base than in A. latin)} : anal segment about the length of the preceding one. Caudal rami resembling in structure those in the said species. Anterior antenna not fully as long as the cephalic segment and composed of 20 articulations. Posterior antennae moderately strong with the penultimate joint about equal in length to the preceding joint. Oral cone shorter than in A. latum, only extending midway between the insertions of the posterior maxillipeds and those of 1st pair of legs. Mandibles, maxillae, maxillipeds and natatory legs differing very little in structure from those parts in A. lattnn. Last pair of legs likewise very similar, though having on the distal joint a small bristle inside the 2 apical setae. Ovisacs of moderate size, oblong oval in form, and somewhat divergent, Colour light greenish. Length of adult female scarcely attaining 0.70 mm. Remark*. This species is closely allied to A. latum, but is of smaller size, and moreover easily distinguishable by the less expanded anterior division of the body, and the evenly rounded lateral parts of the trunk-segments. Finally, the oral cone is considerably shorter than in A. latum. Occurrence. I collected this form, many years ago, in the upper part of the Christiania Fjord, and. on account of its peculiar colour, noted it with the provisional name .4. virescens. I have also found it occasionally off the south coast, at Grimstad and Lillesand. All the specimens were taken in the free state among dredged material. Distribution. Gulf of Naples (Giesbrecht), coast of France (Canu). 93 G-en. is. Eehinoeheres, ciaus. isso. Generic Characters. Body less depressed than in Aseomyzon, the dorsal face of the anterior division being rather strongly vaulted. Tail, as in that genus, composed in female of 3, in male of 4 segments. Anterior antennae much shorter and stouter than in Ascomyzon, though composed of a similar number of articul- ations. Posterior antennae of comparatively feeble structure. Oral cone very short. Mandibles with the palp uniarticulate. Maxillae with one of the setse of the inner lobe excessively developed. Haxillipeds comparatively short and stout. Natatory legs very fully developed, with the rami unusually broad ; their armature about as in Aseomyzon. Last pair of legs with the proximal joint small and indistinctly defined from the segment, distal joint well developed, lamelliform. Remarks. This genus was established in the year 1889 by Glaus, to include 2 species found by him as parasites on Ecbinids. Giesbrecht, however, did not admit this genus, but referred the species to the genus Asterocheres (= Aseomyzon), and this view was also adopted by Scott. On a closer exami- nation of the type species, I find, however, that in some points it differs so con- spicuously from the other species of the genus Aseomyzon, that in my opinion the Clausian genus ought to be supported. As to the term Eehinoeheres, the same objection could perhaps be urged against it as against the term Astero- cheres: but as in fact both species have hitherto been found exclusively on Echinids, I do not find in the present case any imperious necessity for rejecting it. Only the type species is represented in the Fauna of Norway. 55. Eehinoeheres violaeeus, Claus. (PI. LVII). Eehinoeheres riolaceus, t'laus. Halbparasitische Gopepoden; Arb. Zool. lust. Wien, Voll. III. Syn: Asterocheres violaeeus. Giesbr. Aseomyzon Thompsoni, A. Scott. Specific Characters. Female. Body robust, with the anterior division considerably tumefied and broadly oval in outline. Cephalic segment large and evenly arched in front; rostral prominence comparatively small, though well defined; lateral edges of the segment inflexed. Epimeral parts of the trunk- segments rounded off at the end; penultimate segment, as usual, much smaller than the preceding one; last segment still smaller. Tail comparatively short, with the genital segment gradually widening in front, and having the lateral edges very finely ciliated; anal segment smaller than the preceding one. Caudal rami about the length of the anal segment and slightly divergent; apical seta? com- paratively short, the 2 middle ones rather thicker, but not much longer than the others, and densely plumose. Anterior antennae much shorter than the cephalic segment, and composed of 20 articulations, terminal part very short, though having all 3 joints well defined. Posterior antennas with the penultimate joint somewhat shorter than the preceding one; terminal joint distinctly subdivided in the middle. Oral cone scarcely extending beyond the insertions of the anterior maxillipeds, and having the outer part abruptly narrowed. Mandibles with the masticatory part narrow styliform. Maxillae with the inner lobe short and thick, transversely truncated at the end; principal seta very largely developed, extending far beyond the insertions of the maxillipeds, and densely plumose; outer lobe much smaller, and having the apical seta3 comparatively short. Max- illipeds rather powerfull; claw of the anterior ones very strong and curved at the end in a hook-like manner. Natatory legs largely developed, with the middle joint of the inner ramus in 1st pair unusually broad and expanded. Last pair of legs with the distal joint oval in form and rounded at the extremity, which carries 2 seise accompanied by a small bristle. Ovisacs comparatively small, oval in form. Colour somewhat variable, in some cases dark violaceous, in other cases much paler. Length of adult female 0.90 1.10 mm. ReiniD'l-x. This form, as above mentioned, was first described by Glaus as the type of his genus Echinoeheres. Another species of smaller size was also recorded by the same author under the name of Echinoeheres minutus, and this species has likewise been observed by Giesbrecht, who admits its specific difference. The very close relationship between these 2 species, both as to structural details and habits, would indeed seem to justify the opinion of Glaus, that they should be kept apart under a separate genus. The Ascomyzon Thompson! of A. Scott is unquestionably identical with the present species. Occurrence. I have taken this form occasionally from 3 different Echi- nids, viz.. Strongylocentrotus flrvbachicu*!* (small variety), Echinus sphcem and Echinus elegans, all collected off the west coast of Norway from different depths. The specimens found on the first-named Echinid were all of a very dark viola- ceous colour, like that indicated in the coloured figure given in Giesbrecht's work on PL 1; whereas those occurring on the other 2 Echinids were much paler, of a whitish grey hue, with a very slight rosy tinge. These specimens were also of a somewhat larger size, but otherwise fully agreeing with the dark- coloured variety. Giesbrecht also mentiones the variability of colour in the pre- sent species. . British Isles (Scott), Triest (Glaus), Gulf of Naples (Giesbrecht). 95 Gen. 19. Dermatomyzon, ciaus. iss<. Syn : Cyclopicera, Brady (part). Generic- Characters. General form of body resembling that in the pre- ceding genus, the anterior division being rather tumid and evenly vaulted above. Tail, however, composed in female of 4, in male- of 5 well-defined segments. Anterior antennae not much elongated, though composed of a considerable number of joints ; those in male imperfectly hinged and, at any rate in some cases, provided with supplementary sensory filaments. Posterior antennae with the penultimate joint comparatively short. Oral cone very little produced. Mandibles with the masticatory part rather strong, knife-shaped ; palp uniarticulate. Maxillae with the inner lobe normal ; outer lobe narrow linear. Maxillipeds of the usual structure; the posterior ones in male without any distinct palmar projection. Natatory legs strongly built, though not very different in structure from those in the preceding genera. Last pair of legs with the proximal joint well defined from the segment; distal joint lamelliform and provided with lateral spines in addition to the apical setae. Remarks. This genus is also closely allied to Ascomyzon, though at once distinguished by the tail having one segment more in both sexes. The genus Cyclopicera of Brady, though of earlier date than Dermatomyzon, cannot properly be retained, because it was originally (in 1872) based upon a species that has turned out to be a true Ascomyzon (A. latum). Two species of the present genus have been described ; but their specific difference has not been admitted by Griesbrecht. 56. Dermatomyzon nigripes (Brady). (PL LIX & LX). Cyplopicera nigripes, Brady, Moiiogr. of British Copepoda, Vol. Ill, p. 54, PI. LXXXIX, figs. 1 11. Syn : Ascomyzon Thorelli, G. 0. Sars. Specific Characters. Female. Anterior division of body rather tumid, broadly oval in outline, with the cephalic segment very large and evenly arched in front; lateral edges of this and the succeeding segment inflexed. Rostrum triangular, but not very prominent. Lateral parts of the trunk-segments obtusely rounded at the end. Tail nearly half the length of the anterior division and having the segments very sharply marked off from each other, each segment being produced at the end on each side to an acute corner; genital segment moderately broad and imperfectly subdivided in the middle, with the lateral edges perfectly smooth; anal segment smaller than the preceding one. Caudal rami comparatively short, !. about the length of the anal segment, and slightly divergent, outer edge smooth, inner finely ciliated, tip obtusely rounded; apical setse of moderate size and somewhat spreading, the innermost but one about equalling the tail in length. Anterior antennae much shorter than the cephalic segment, and composed of 19 joints, terminal part bi-articulate. Posterior antennae with the penultimate joint scarcely more than half as long as the preceding one; apical spine rather strong. Oral cone comparatively small, extending only slightly beyond the insertions of the anterior maxillipeds, and terminating in a sharp point apparently formed by the extremity of the posterior lip. Masticatory part of mandibles cultriform, with a very fine denticulation on the inner edge of the extremity. Maxillae with the inner lobe somewhat curved and tapered distally, apical setae comparatively short; outer lobe very narrow, linear, with the apical setae longer than those on the inner lobe. Anterior maxillipeds rather powerful, with the claw very strong and slightly curved at the end. Posterior maxillipeds of the usual structure. Natatory legs differing a little in their armature from those in the preceding forms, the terminal joint of the outer ramus being provided inside in 1st pair with 3, in 2nd pair with 5 set*; same joint of inner ramus in the last 2 pairs with only a single spine on the tip. Last pair of legs with the distal joint rounded oval in form, and armed on the hind edge with 2 blunt spines, the extremity car- rying 2 setae accompanied inside by a small bristle. Ovisacs comparatively small, rounded oval in form. Male, as usual, smaller than female, and having the anterior division far less dilated. Tail with the segments still more sharply marked off from each other; genital segment greatly swollen. Anterior antennae 17-articulate, and each provided with about 7 supplementary sensory filaments curving backwards. Body in both sexes generally of a brownish grey hue, with the anterior antennae and natatory legs very dark-coloured, almost black; tail also partly tinged with a dark brownish colour. Length of adult female amounting to 1 55 mm., of male to 1.20 mm. Remarks. This form was recorded as early as the year 1875 by Brady & Robertson under the name of Cydopicera n\<'*. and was justly referred b} Giesbrecht to the genus Dermatomyzon, as defined by Glaus. It seems however very questionable to me, if Giesbrecht was right in identifying the form described by Glaus under the name Dermatomyzon dei/tni* with the present species, as the latter differs not only in its much larger size and peculiar coloration of the body, but also in the presence on the male anterior antennae of greatly developed supplementary sensory filaments. Tliese filaments, according to ( 'ami, are wholly absent in the male of D. elegam. Occurrence. I have met with this form not unfreijiiently along the whole Norwegian coast, from the upper part of the (Jhristiania Fjord to Vads0, in moderate depths. All the specimens have been taken in the free state among dredged material, and, though the parasitic habits of the animal are proved by the structure of the oral parts, we do not as yet posess any information as to what kind of invertebrate animals are at times infested by it. Distribution. British Isles (Brady), Spitsbergen (G. 0. Sars), Franz Joseph Land (Scott), ? Gulf of Naples (Giesbrecht). Gen. 20. RhynchOmyZOIl, Giesbrecht, 1895. Generic Characters. Body more slender than in the preceding genera, with the anterior division far less expanded, and some of the trunk-segments acutely produced laterally, liostrum large and prominent, curved downwards. Tail comparatively slender, consisting in female of 4, in male of 5 segments. Caudal rami more or less produced. Anterior antennae of moderate length, and composed of a varying number of articulations; those in male imperfectly hinged and without any supplementary sensory filaments. Posterior antennae resembling in structure those in Dermatomyzon. Oral cone short and massive, not prolonged in any siphonal tube. Mandibles with the masticatory part more or less cultri- form; palp very small, uniarticulate. Maxillae and maxillipeds about as in Der- matomyzon. Natatory legs well developed, and on the whole normally built. Last pair of legs comparatively small, biarticulate, distal joint of somewhat dif- ferent shape in the different species. Remarks. This genus, established by Giesbrecht, differs conspicuously, as to the external appearance of the body, from the preceding ones, though in the structural details approaching somewhat the genus Dermatomyzon. One of the most conspicuous external characters is the very large and prominent falci- form rostrum, which indeed has given rise to the generic name proposed by Giesbrecht. The genus comprises as yet 3 well-defined species, 2 of which will be described below, the 3rd species, R. falco Giesbrecht, being hitherto only known from the Gulf of Naples. 13 Crustacea. 57. Rhynehomyzon purpurocinetum, (Scott). (PI. LXI). Ciiplopicera purpurocincta, Scott. Eleventh Ann. Eep. of the Fishery Board for Scotland. Part III p. 209, PL III, figs. 29-40 Specific Characters. Female. Anterior division of body rather strongly vaulted above, and oblong oval in outline, greatest width scarcely exceeding half the length. Cephalic segment large, being fully twice as long as the 4 succeeding segments combined, aud having the frontal edge narrowly arched, epimeral edges of the segment evenly curved in front and strengthened behind by a number of transverse chitinous stripes. Rostrum very conspicuous in the lateral aspect of the animal, and produced to a sharp point. Epimeral parts of the 2 succeeding segments terminating behind in acute corners. Tail about equalling in length 2 /s of the anterior division: genital segment almost cylindric in form, with a very slight angular prominence on each side of the anterior part; 2nd segment almost as long as the 2 succeeding segments combined; anal segment the smallest. Caudal rami rather produced, somewhat exceeding in length the last 2 segments com- bined, and slightly divergent, outer edge smooth, inner finely ciliated; apical setse comparatively short, the innermost but one scarcely exceeding twice the length of the corresponding ramus. Anterior antennae rather narrow, but much shorter than the cephalic segment, and composed of 16 joints only, 2nd joint the largest and apparently formed by the fusion of 4 short joints: terminal part biarticulate. Posterior antenna with the penultimate joint scarcely half as long as the pre- ceding one; apical spine rather slender. Oral cone very massive and rather prominent below; anterior lip terminating in a somewhat curved point. Mandibles with the masticatory part pronouncedly knife-shaped and minutely denticulate inside the tip. Maxillse with the outer lobe nearly as long as the inner, but much narrower, linear in form; setse on both lobes comparatively short. Max- illipeds moderately strong. Natatory legs exhibiting a similar armature to that in Dermatomyzon nigripes. Last pair of legs with the distal joint oval in form and subtruncate at the extremity, which carries 2 thin bristles between which a somewhat larger lanceolate spine is attached; posterior edge of the joint finely ciliated and having on each side of the innermost bristle a slight dentiform projection. Male much smaller than female, but not very different in the general form of the body. Tail, however, somewhat more slender and composed of 5 well-defined segments, the foremost of which (the genital segment) is compara- tively smaller than in most other forms of the present section. Anterior 99 antenna; very imperfectly hinged and composed of only 14 joints. Last pair of legs differing from those in female by the presence on the distal joint of 3 additional spines attached to the inner edge. Body in both sexes of a whitish colour, with a broad dark purplish, or almost black band across the posterior part of the trunk, occupying the whole of the 2nd, 3rd and 4th segments. Rostrum of a similar colour, and the anterior antennae, the natatory legs, and the ends of the caudal rami also more or less dark in colour. Length of adult female amounting to l.<>3 mm., of male to <>.73 mm. Remarks. This is a very distinct and easily recognisable form. It was at tirst recorded by Scott as a species of the genus Cyclopicera Brady, but was subsequently justly removed from that genus by Giesbrecht, and referred to his new genus Ehynchomyzon. The present species may be regarded as the type of that genus. Occurrence. I have only met with this form quite occasionally at Aale- sund and Christiansund, west coast of Norway. The specimens were found in moderate depths among dredged material. Distribution. British Isles (Scott), Gulf of Naples (Giesbrecht). 58. Rhynchomyzon rubrovittatum, G. 0. Sars, n. sp. (PI. LXII). Specific Characters. Female. Anterior division of body less strongly vaulted above than in the preceding species, and, viewed dorsally, of a some- what irregular oblong oval form. Cephalic segment not quite twice as long as the 4 succeeding ones combined, and narrowly rounded in front, epimeral edges of the segment evenly curved. Rostrum very large, falciform, and terminating in an acuminate point. Antepenultimate trunk-segment produced on each side to a prominent acute process pointing obliquely backwards; penultimate segment, as usual, much smaller, with the lateral parts broadly rounded; last segment scarcely broader than the genital segment. Tail exceeding somewhat in length 2 / 3 of the anterior division ; genital segment slightly dilated in front and produced on each side to a spiniform, posteriorly pointing process ; the succeeding segments gradually diminishing in size, and, combined, about the length of the genital one. Caudal rami rather produced, exceeding in length the last 2 segments combined, and somewhat divergent, outer edge perfectly smooth and produced at the end to a well-marked dentiform projection, inner edge finely ciliated; apical seta? com- I M ) paratively short. Anterior antennae very slender, almost attaining the length of the cephalic segment, and composed of 20 joints, terminal part comparatively small and, as in the preceding species, biarticulate. Posterior antennae about as in that species. Oral cone very short and abruptly contracted at the extremity. Mandibles with the masticatory part less strong than in the type species, and scarcely denticulated at the tip. Maxillae with both lobes comparatively shorter. Anterior maxillipeds with the claw imperfectly biarticulate. Posterior maxillipeds rather slender, with a thin bristle in the middle of the palmar edge. Natatory legs with the spines of the outer ramus rather broad, lancet-shaped and distinctly denticulated at the edges; terminal joint of this ramus in 1st pair with only 2 setae inside, that of 2nd pair with 4 such setae. Last pair of legs with the distal joint rather short and projecting into 2 unequal dentiform processes, between which 2 likewise unequal bristles are attached. Colour rather peculiar: anterior division of body of a clear whitish hue, with a number of narrow transverse bands of a bright red colour, 3 of them occupying the hindmost part of the 3 anterior segments, 2 others, of a more irregular form, crossing the cephalic segment in front of the middle. Tail and anterior antennae of a beautiful rosy hue. Length of adult female about 1 mm. Male unknown. Remarks. This form is at once distinguishable from both of the 2 hitherto recorded species, though evidently belonging to the same genus. The specific name is derived from the very peculiar and beautiful colour of the body, when alive. Occurrence. Only a solitary female specimen of this handsame form has come under my notice. It was taken, many years ago, at Kallevaag, west coast of Norway, from a depth of about 50 fathoms, among dredged material. Gen. ->\. COllOChereS, Canu, 1893. Syn: Cyclopicera, Brady (part). ,, Clausomyzon, Giesbrecht. (rcneric Characters. Body of very slender form, with the anterior division only slightly dilated and somewhat compressed in front; rostrum comparatively small, but acutely produced. Epimeral parts of the trunk-segments rounded off. Tail composed in female of 4, in male of 5 segments. Caudal rami long and 101 narrow, with the outermost seta more or less remote from the apex Anterior antennae slender, resembling in structure those in the genus Ascomyzon, though having the proximal and distal portions less sharply marked off from each other; those in male distinctly hinged. Posterior antennae of normal structure. Oral cone not much prolonged, pyriform in shape. Mandibles with the masticatory part moderately slender; palp small, uniarticulate. Maxillae with the outer lobe much narrower than the inner, and tipped with only a single seta. Maxillipeds comparatively slender; claw of the anterior ones distinctly biarticulate. Natatory legs with the rami rather narrow ; their armature about as in Dermatomyzon. Last pair of legs with the distal joint more or less prolonged. Remarks. This genus was established in the year 1893 by (.'ami. to include the species recorded by Brady as Cijclopim-a gracilicauda. Another nearly-allied species has been described by Giesbrecht from the Gulf of Naples tinder the name of C. Canui and a 3rd species, C. eleyans, has been added by A. Scott. The last-named species differs however in some points so much from the other two, that I have felt justified in removing it to a separate genus To the Fauna of Norway only belongs the type species, to be decribed below. 59. Collocheres graeilicauda, (Brady). (I'l. LXIII). Ci/plopicent gracilicauda, Brady, Monogr. British < 'opepuda, Vol. Ill, p. 58. I'l. LXXXITI. fis. 110. Syn : .\*<-i>iiu/:o/i niiiii'ifiilcp. Clait gracilicauda, (iiesbr. Specific Characters. Female. Anterior division of body, viewed dorsally, regularly oblong oval in outline, with the greatest width about equalling half the length. Cephalic segment large and very deep, the epimeral edges being angu- larly curved in the middle; rostrum not very large, but distinctly prominent below, and acutely pointed. Last trunk-segment very small, scarcely broader than the genital segment. Tail slender and elongated, being not much shorter than the anterior division; genital segment large and somewhat dilated in the middle; the 3 succeeding segments gradually diminishing in size. Caudal rami exceedingly long and narrow, almost attaining half the length of the tail, and slightly divergent, both edges smooth; outermost apical seta short, spiniform, and, together with the dorsal bristle, somewhat remote from the apex, which projects outside to a short dentiform process; inner mediate seta scarcely exceeding in length the corresponding ramus. Anterior antennae almost as long as the cephalic segment, and composed of 2<> joints, terminal part biarticulate. Posterior antennae with the penultimate joint scarcely more than half as long as the preceding one; rudi- mentary outer rarmis remote from the end of the latter joint, being attached nearly at the middle of its posterior edge. Oral cone extending only to the insertions of the posterior maxillipeds, and gradually tapered. Mandibles with the mas- ticatory part moderately slender, and distinctly denticulated inside the tip; palp with only a single apical seta. Maxillee with the outer lobe a little shorter than the inner, and much narrower, apical seta rather elongated and accompanied by a small hair. Claw of anterior maxillipeds very slender and distinctly subdivided in the middle, outer part evenly curved. Posterior maxillipeds, as usual, more elongated than the anterior ones. Natatory legs of rather feeble structure, the rami, especially in the 4th pair, being unusually narrow. Last pair of legs with the proximal joint well defined from the segment, and produced inside to an acuminate process; distal joint very long and slender, sabre like, and extending far beyond the middle of the genital segment, outer edge produced, at some distance from the end, to a dentiform projection, the apical part, beyond the process, being provided with 3 or 4 small bristles. Male, as usual smaller than female, and of still more slender shape. Anterior antennse composed of 19 joints, the last 2 of which admit of being bent upon the adjoining part. Last pair of legs difiering somewhat from those in female, the distal joint being comparatively shorter and almost claviforra in shape, and -moreover provided with 2 additional blunt spines inside. Genital lobes bipartite. Body in both sexes very pellucid and nearly colourless. Length of adult female amounting to 0.85 mm., of male to 0.68 mm. Remarks. As mentioned above, this form was first described by Brady as a species of his genus Cyclopicera. It was subsequently justly removed from that genus by Canu and placed in the new genus Collocheres established by that author. According to the same author, the Ascomyzon comatulce of Rosoll is identical with the present species. Occurrence. I have hitherto only met with this form in a single locality, viz., at Ris0r, south coast of Norway, where a few specimens were taken from a depth of about 30 fathoms among dredged material. Rosoll found this form parasitic on Comatula mediterranea. Distribution. British Isles (Brady), coast of France (Canu), Triest (Rosoll), Gulf of Naples (Giesbrecht). Gen. -2-2. MeSOCliereS, Norm. & Scott, 1905. Generic Characters. Body slender and elongated, with the anterior division only slightly dilated. Cephalic segment less deep than in Collocheres with the rostrum comparatively small. Epimeral parts of the trunk-segments slightly produced. Tail slender, and composed in female of only 3 segments. < 'audal rami long and narrow. Anterior antennae slender, resembling in structure those in Ascomyzon. Posterior antennae moderately strong, with the penultimate joint comparatively short. Oral cone very little produced. Mandibles with the masticatory part comparatively short, tapered and minutely denticulated inside the tip; palp small, uniarticulate. Maxilla? with the lobes likewise rather small, the inner one being the larger. Anterior maxillipeds distinguished by the pre- sence of a secondary spine at the base of the claw. Posterior maxillipeds of normal structure. Natatory legs rather strongly built, with the spines unusually broad, dagger-like. Last pair of legs very small, biarticulate, distal joint tri- angular in shape. Remarlcs. With regard to the general form of the body and the long and narrow caudal rami, this genus somewhat recalls the preceding one, from which it is, however, at once distinguished by the different segmentation of the tail, in which respect it agrees with the genus Ascomyzon. In the other structural details also, several peculiarities are found to exist, fully justifying the establish- ment of the present genus. It comprises as yet only a single species, to be described below. 60. Mesocheres anglicus, Norm. & Scott. (PI. LXIV). Mcsoclier.es anglicus. Norm. & Scott, Crustacea Copepoda new to science, Ann. & Mag. Nat. Hist. Ser. 7. Vol. XV, p. 298. Specific Characters. Female. Anterior division of body oblong oval in outline, with the greatest width about equalling half the length. Cephalic seg- ment large and narrowly rounded in front, epimeral edge gently curved; rostrum acutely produced below. Lateral parts of the 3 succeeding segments somewhat angular behind. Last segment very small, scarcely broader than the genital segment. Tail somewhat shorter than the anterior division, and very narrow; genital segment about the length of the other 2 combined, and slightly dilated 104 in its anterior part, which projects on each side to a hamiform, posteriorly- pointing process; anal segment much smaller than the preceding one. Caudal ratni exceedingly long and slender, linear, attaining about the length of the remaining part of the tail, and only very slightly divergent; outer edge very finely ciliated, inner smooth, tip transversely truncated; apical setae comparatively short, the innermost but one scarcely longer than the corresponding ramus. Anterior antenna? not quite as long as the cephalic segment, and composed of 21 well-defined joints, terminal part distinctly 3-articulate. Posterior antennae with the penultimate joint scarcely half as long as the preceding one; rudimentary outer ramus attached close to the end of the latter joint. Oral cone very short, almost globular in form, its extremity being obtusely blunted and only extending to the insertions of the anterior maxillipeds. Mandibles and maxillae pointing almost straight inwards. Anterior maxillipeds with the claw rather slender and evenly curved in its outer part, basal spine rather strong and likewise curved. Posterior maxillipeds comparatively slender. Natatory legs with the number of set&e about as in Axcjmij'.on: spines distinguished by their broad dagger-like form and the coarse denticulation of their edges. Last pair of legs with the proximal joint well defined and of the usual appearance, distal joint rounded triangular in form and provided with 2 small apical bristles and 2 lateral ones, that of the outer edge the longer. Ovisacs, in the specimen examined, very small, each containing only 3 ova, arranged in a single row. Body of a clear whitish colour, partly tinged with reddish orange; ovarial tubes dark green. Length of adult female about 1 mm. Male unknown. Remarks. This form was first anounced under the above name by Norman & Scott in the year 195 from a single female specimen taken in Plymouth Sound. In the following year this specimen was redescribed and figured in detail by the same authors in their work on the Crustacea of Devon and Cornwall. Occtirii'iice. Only a few female specimens of this form have hitherto come under my notice. They were taken, many years ago, in the upper part of the Christiania Fjord from a depth of about 30 fathoms among dredged material. Distribution. British Isles (Norman & Scott). Cyclopidae Copepoda Cyclopoida Pi. XLIX G. O. Sars, del. Platycyclops affinis, G. O. Sars Cyclopidae Copepoda Cyclopoida Pi. L G. O. Sars, del. Platycyclops fimbriatus, (Fischer) Ascomyzontidae Copepoda Cyclopoida Pi. LI LI G. O. Sars, del. Ascomyzon asterocheres, Boeck Ascomyzontidse Copepoda Cyclopoida PI. LII G. O. Sars, del. Ascomyzon asterocheres, Boeck (continued) Ascomyzontidae Copepoda Cyclopoida PL LIII G. O. Sars, del. Ascomyzon Lilljeborgi, Thorell Ascomyzontidae Copepoda Cyclopoida PL LIV G. O. Sars, del. Ascomyzon Boecki, (Brady) Ascomyzontidae Copepoda Cyclopoida PI. LV . - // G. O. Sars, del. Ascomyzon simulans, Scott Ascomyzontidae Copepoda Cyclopoida Pi. LVI G. O. Sars, del. Ascomyzon latum, (Brady) Ascomyzontidae Copepoda Cyclopoida PI. LVII G. O. Sars, del. Ascomyzon parvum, (Giesbrecht) Ascomyzontidae Copepoda Cyclopoida PI. LVIII G. O Sars, del. Echinocheres violaceus, Claus Ascomyzontidse Copepoda Cyclopoida Pi. LIX vv G. O. Sars, del. Dermatomyzon nigripes, (Brady) Ascomyzontidae Copepoda Cyclopoida PI. LX G. O. Sars, del. Derrnatomyzon nigripes, (Brady) (continued) Ascomyzontidae Copepoda Cyclopoida PI. LXI G. O. Sars, del. Rhynchomyzon purpurocinctum, (Scott) Ascornyzontidae Copepoda Cyclopoida PI. LXII G. O Sars, del. Rhynchomyzon rubrovittatum, G. O. Sars Ascomyzontidae Copepoda Cyclopoida PI LXIII a'. I G. O. Sars, del. Collocheres gracilicauda (Brady) Ascomyzontidae Copepoda Cyclopoida PI. LXIV rf ^ G. O. Sars, del. Mesocheres anglicus. Norm. & Scott AN ACCOUNT OF THE CRUSTACEA OF NORWAY WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES G. O. SARS VOL. VI COPEPODA CYCLOPOIDA PARTS IX & X ASCOMYZONTID^ (concluded), ACONTIOPHORID^E, MYZOPON- TIIDJE, DYSPONTIID.E, ARTOTROGID^, CANCERILLID^ \\ rill Hi \1 Til i Yl'IC I'l.ATKS BERGEN PUBLISHED BY THE BERGEN MUSEUM iO'tD BY ALB. CAMJNIKKMEYEB'S FORLAG. CHKISTIANIA 1915 105 Gen. 23. LeptOHiyzOn, Or. 0. Sars, ri. Syn: Collocheres, A. Scott (part). Generic Characters, Body slender, with the anterior division very little dilated. Cephalic segment with the inferior edges considerably curved in front; rostral projection very slight and obtuse at the tip. Epimeral plates of the succeeding segments rounded off. Tail very slender, and composed in female of 4 well-defined segments; genital segment without any lateral projections. Caudal rami somewhat produced, though far less slender than in the 2 preceding genera, outer seta more or less remote from the apex, dorsal bristle, however, occupying its usual place near the end of the ramus. Anterior antennae slender, with the full number of articulations. Posterior an term se resembling in structure those in Collocheres. Oral cone short and stout, carrying at the obtuse apex 2 remark- able diverging tentacular appendages, apparently attached to the posterior lip. Mandibles rather strong, with the apex distinctly denticulate, palp small, con- sisting of a narrow cylindrical joint, carrying on the tip a ciliated seta. Maxilla? with the inner lobe well developed and furnished at the end with 4 rather strong setae; outer lobe much narrower, but of about the same length, and provided with only a single apical seta. Maxillipeds with the dactyli extremely slender, that of the anterior ones distinctly biarticulate. Natatory legs well developed, with the rami comparatively broader than in Collocheres : their armature about as in that genus. Last pair of legs distinctly biarticulate, proximal joint forming inside a lingui- form expansion, distal joint rather large, oblong, and extending backwards along the genital segment. Remarks. The present new genus is established to include the form described by A. Scott as Collocheres elegans. This form, it is true, exhibits some characters in common with the type of the genus Collocheres, but differs in other particulars so materially, that in my opinion it ought to be kept apart as the type of a distinct, though nearly-allied genus. The chief differences are found in the structure of the oral cone, the last pair of legs and the caudal rarni. In addition to the type species described below, the form recorded by A. Scott from Ceylon as Collocheres Giesbrechti is undoubtedly referable to the present genus. 61. Leptomyzon elegans, (A. Scott). (PI. LXV). Collocheres clegans, A. Scott. Report for 1895 of the Lancashire Sea-Fisheries Lahoratoritmi. p. 52, PL V, figs. 615. Specific Characters. Female. Body exceedingly slender and elongated, with the anterior division oblong fusiform in outline, greatest width scarcely 14 Crustacea. 106 exceeding half the length. Cephalic segment somewhat longer than the 4 suc- ceeding segments combined, and narrowly rounded in front. Tail slender, almost attaining the length of the anterior division; genital segment rather large, exceeding in length the 3 succeeding segments combined, and slightly dilated in its anterior part. Caudal rami rather produced, being about the length of the last 2 segments combined, and somewhat lamellar, with the outer part slightly narrowed, inner edge finely ciliated; outermost seta at a considerable distance from the apex, and attached to a distinct ledge on the exterior margin, innermost seta slender, exceeding the corresponding ramus in length; the inner mediate one about half the length of the tail. Anterior antennae nearly as long as the cephalic segment, and composed of 21 joints, the outer 3 constituting the ter- minal part. Posterior antennae with the outer ramus very small and attached about in the middle of the very slender 2nd joint. Natatory legs of a similar structure to that in Collocheres gracUicaudtt, but more strongly built, especially the 4th pair. Last pair of legs scarcely extending beyond the middle of the genital segment; inner expansion of proximal joint obtusely triangular in form, unarmed ; distal joint oblong oval in form, with the inner edge straight, outer gently curved and minutely ciliated, tip obliquely truncated and provided with 3 small bristles. Body rather pellucid, of a whitish grey colour. Length of adult female 0.87 inm. Male unknown. Remarks. This form, as already mentioned, was described by A. Scott as a species of the genus Collocheres, the characteristic structure of the oral tube having escaped his attention, as also the difference in the arrangement of the caudal seta?. Occurrence. A few female specimens of this form were collected, many years ago, at Eggesb0noes, west coast of Norway, from a depth of about 20 fathoms. Distribution. Off Port Erin, west coast of Scotland (A. Scott). Gen. 24. SCOttOChereS, Giesbrecht 1897, Syn: Acontiophorufi. Scott (part). Generic Characters. Body of a similar slender form to that in the 3 preceding genera, the anterior division being only slightly dilated. Cephalic segment scarcely compressed, its inferior edges being quite evenly curved; rostrum 107 wholly absent. Epimeral parts of the 3 succeeding segments rounded off. Tail composed in female of only 3, in male of 4 segments. Caudal rami not much produced, in some cases very short, with all the setae originating from the end. Anterior antennae resembling in structure those in the other Ascomyzontidce, though having the number of joints somewhat reduced; those in male distinctly hinged and provided with supplementary sesthetasks. Posterior antennae of the usual appearance. Oral cone, however, rather peculiar and somewhat similar to that in the next family, being produced into a very narrow, more or less curved siphonal tube. Mandibles without any palp, and having the masticatory part extremely slender, setiform. Maxillae with the lobes very unequal in size, each carrying 3 setae. Maxillipeds comparatively slender, with the dactyli exceedingly narrow, that of the anterior ones distinctly biarticulate. Natatory legs well developed, with the rami comparatively broad and equal-sized; their armature differing slightly from that in the other genera. Last pair of legs of moderate size, biarticulate, proximal joint broadly expanded inside, distal joint lamelliform. Remarks. This genus was established by Giesbrecht, to include the form at first described by Scott as Acontlopliorns elongates. The differences of this form from the true Acontlopliori have been duly pointed out by Giesbrecht. Indeed, the only character by which it seems to approach that genus, is the structure of the siphon. Otherwise it agrees fairly well with the other Ascomy- zontidce, and of course ought to be included in that family as here defined. In addition to the type species described below, Giesbrecht records another nearly- allied form from the Bay of Naples under the name of S. longifurca. 62. Scottocheres elongatus, (Scott). (PI. LXVI). ruf; elortgahift, Scott. Ann. & Mag. Nat. Hist.. Ser. 6. Vol. XII. p. 145, PI. IX, figs. 1520. Specific Characters. Female. Body comparatively narrow and elongated, with the anterior division oblong in form, greatest width scarcely exceeding half the length. Cephalic segment of moderate size and obtusely rounded in front, without any trace of a rostral projection below. The 3 succeeding segments gradually diminishing in size, with the epimeral parts not very prominent. Tail scarcely exceeding half the length of the anterior division ; genital segment com- paratively large, occupying more than half the length of the tail, and somewhat dilated in its anterior part, with a slight prominence on each side, just in front of the genital orifices; anal segment very small, scarcely half as long as the 108 preceding segment. Caudal rami short, quadrangular in form, being scarcely longer than they are broad, and transversely truncated at the end; apical setse of moderate length, the outer mediate one remarkably thickened in its middle part. Anterior antennae not nearly attaining the length of the cephalic segment and rather narrow, being composed of 17 joints sparingly clothed with com- paratively small setse, proximal division well marked off from the distal one, terminal part uniarticulate. Posterior antennae with the 2nd (basal) joint rather slender, rudimentary outer rarnus attached near the end of this joint; terminal joint very small, but with the apical spine rather strong. Siphon extending about to the end of the anterior division of the body, being, as a rule, conspicuously curved, and in preserved specimens often split up into its two components, the anterior and posterior lips. 1st pair of natatory legs with the spine, issuing from the 2nd basal joint inside, lanceolate in form; terminal joint of outer ramus with only 2 seise, inside, distal spine of outer edge well developed, the other 2 very small. Same joint in 2nd and 3rd pairs with 4. in 4th pair with 3 setae inside. Terminal joint of inner ramus in 1st pair with a conspicuous dentiform projection inside the tip; same joint in 4th pair with only a single apical spine. Last pair of legs with the inner expansion of proximal joint broadly rounded, unarmed; distal joint oval in form, with the edges minutely ciliated and the tip provided with 3 comparatively short seta3, the middle one spiniform. Male resembling the female in the general shape of the body, but of smaller size, and having the tail composed of 4 well defined segments, the 1st of which is considerably swollen, to receive the comparatively large globular spermatophores- Anterior antennae much more powerfully developed than in female, though composed of a smaller number of joints, viz., 15, the last 2 of which form together a movable terminal section, which admits of being bent upon the somewhat thickened adjoining part of the antenna. Body (in female) rather pellucid, with a faint orange tinge, and with the translucent ovarial tubes of a somewhat darker hue. Length of adult female about 1 mm., of male 0.7<> mm. Remarks. This form, as mentioned above, was at first described by Scott as a species of the genus Acontioplwrus. apparently on account of the somewhat similar structure of the siphon. Its generic difference has however subsequently been admitted by that author, and it was redescribed under the above name in the sixteenth Annual Eeport of the Fishery Board for Scotland. From the nearly-allied Neapolitan species, S. longifurca Giesbr., it is easily distinguished by the very short caudal rami. 109 Occurrence. A few female specimens of this form were collected, many years ago, at Eggesb0nses, west coast of Norway, and some additional specimens, among them a single male, were recently picked up from the residue of the same collecting bottle, in which, as mentioned above, several species of Ascomyzon were found. Distribution. British Isles (Scott), Bay of Naples (Giesbrecht), Ceylon (A. Scott). Fam, 5. Acontiophoridae. Characters. General form of body resembling that in the Ascomyzontidce, the anterior division being more or less dilated, the posterior one attenuated. Anterior antennae not much produced, and densely clothed with partly ciliated setse, no distinct boundary being found, as in most of the Ascomyzontidw, between the proximal and distal portions; a small terminal part, however, distinguishable, formed by the outermost joints succeeding that carrying the usual sesthetask. Posterior antennae rather unlike those in the Ascomyzontidce, the terminal joint being much more fully developed and provided with several spines and setse; outer ramus comparatively large, though uniarticulate. Oral cone produced into a very narrow siphonal tube somewhat resembling that in Scottocheres. Mandibles with the masticatory part imperfectly developed, terminating in a simple hair- like point, which does not extend to the end of the tube; palp replaced by a single very large and densely plumose seta. Maxillae with the basal part unusu- ally large and massive, lobes more or less curved downwards and provided with richly ciliated setae. Maxillipeds of the usual structure. Natatory legs likewise on the whole normally built. Last pair of legs comparatively small, with the proximal joint imperfectly defined; distal joint scarcely lamellar, and provided with several spiniform setse. Remarks. This family is established to include the genus Acontiopliurus of Brady, which seems to me to differ in some respects so materially from the preceding genera comprised within the family Ascomyzontido}, that it can hardly be associated with them. The structure of the posterior antennse and the oral parts, in particular, is very unlike that found in the true Ascomyzontido:. I am inclined to believe that the 2 hitherto known species, A. suctatus and orniitti*. should more properly be regarded as types of 2 nearly-allied genera, as their outward appearance is rather dissimilar, and some of the structural details also 110 seem to exhibit differences of more than specific value. In any case, the species described below, as the first one recorded, ought to be regarded as the type of the genus Acontiophorus. Gen. 25. ACOntiOphOFUS, Brady 1880. Syu: Soknostoma, Brady (preoccupied). Generic Character*. Anterior division of body moderately dilated, not depressed. Epimeral parts of the trunk-segments not produced, but evenly rounded off. Tail composed in female of 3, in male of 4 segments, none of them pro- duced at the postero-lateral corners. Caudal rarni of moderate size, and trans- versely truncated at the end, apical setse well developed. Anterior antennae very short, with the number of joints considerably reduced ; those in male imperfectly hinged, and provided with supplementary sesthetasks. Posterior antennae with the terminal joint rather large and scarcely narrowed distally, outer ramus attached close to the end of the 2nd (basal) joint, and cylindrical in form. Siphon exceedingly slender and elongated. Maxillse . with the inner lobe larger than the outer, and carrying on the tip 4 setse, the 2 inner of which are densely plumose. Maxillipeds quite normal. Natatory legs with the rami comparatively slender and subequal in length; their armature resembling that in the gen. ScottocJieres. Last pair of legs very small ; distal joint provided with 5 rather unequal setse. Remarks. The above-given generic diagnosis chiefly refers to the type species A. scutatus. The other species referred to this genus, A. ornatus, differs more or less in some of the characters here 'given, and should in my opinion, as noted above, more properly be removed to a separate, though closely-allied genus. 63. Acontiophorus seutatus, Brady. (PI. LXVII). Aritii>1it->riis scutatm. Brady. Mouogr. of British ( 'upepoda. Vol. III. p. H9. I'l. XC. %s. 1 10. Syn: Solenostoma scutatwn, Brady & Roberts. Specific Characters. Female. Body moderately slender, obpyriform in shape, with the anterior division broadly ovate, greatest width considerably ex- ceeding half the length. Cephalic segment very large, occupying nearly half the length of the body, and quite evenly rounded in front; rostral projection extremely small, almost obsolete. Tail scarcely exceeding in length 1 / 3 of the anterior Ill division and having all the segments quite simple ; genital segment about the length of the 2 succeeding segments combined and slightly dilated in front. Caudal rami sublinear in form, being about 3 times as long as they are broad, and scarcely at all divergent; apical setoe more or less curved outwards in their distal part, the inner mediate one exceeding the tail in length. Anterior antennse short and rather thick at the base, tapering distally, and composed of only 1 1 joints clothed with slender spreading setse, 1st, 2nd and 6th joints larger than the others ; terminal part 3-articulate. Posterior antenna3 fully as long as the anterior ones, and having the 2nd (basal) joint comparatively large and slightly curved in the middle, terminal joint exceeding somewhat in size the preceding one, and carrying on the blunted end 2 comparatively large spines of unequal length and finely denticulated on the edges, these spines being moreover accom- panied inside by a slender ciliated seta, and outside by a somewhat shorter seta and a minute bristle; outer ramus somewhat longer than the terminal joint and provided with a long apical seta and another much shorter lateral one. Siphonal tube exceedingly long and slender, extending almost to the end of the body. Maxillae with the outer lobe originating far in front and considerably curved, carrying on the tip 3 moderately long plumose setse accompanied outside by a minute bristle. Maxillipeds moderately strong, dactylus of the anterior ones only slightly curved and imperfectly subdivided in the middle; basal part of the posterior ones composed of 2 well-defined joints. Natatory legs with the spines of the outer ramus narrow lancet-shaped; terminal joint of this ramus in 1st and 4th pairs with 3 setse inside; terminal joint of inner ramus in 3rd and 4th pair with only a single spine on the tip. Last pair of legs with the distal joint rather small, rounded oval in form, and carrying inside 2 short setse, outside 2 much longer setse attached close together to a distinct ledge and partly crossing each other, and at the somewhat exserted tip another similar seta. Ovisacs oblong in form, and closely appressed to the tail, each containing a rather limited number of ova, in some cases only 4 arranged in a single row. Male considerably smaller than female, and exhibiting the usual sexual differences. Anterior antennse composed of the same number of joints as in the female, though their mutual relation is rather different; terminal part consisting of only a single narrow lamellar joint; sesthetask issuing from the preceding joint very largely developed. Colour (in female) generally light yellowish brown, with darker intestine and ovarial tubes. Length of adult female about 1 mm. Remarks. This form was at first recorded by Messrs. Brady and Robertson under the name of Solenostoma scMtatum. The generic name being however preoccupied, it was redescribed and figured by the former author in his monograph under the above name. It is a very distinct and easily recognizable form, especially distinguished by the unusually short anterior antennae and the extraordinary development of the siphon. Occurrence, I have met with this form in 2 different localities on the west coast of Norway, viz., at Kalvaag and Aalesund. In the latter place it occurred not unfrequently at a depth of about 10 fathoms among algse and other marine growths. Distribution. British Isles (Brady), coast of France (Canu), Mediter- ranean (Claus, Giesbrecht). Fam. 6. Myzopontiidae, Characters. General form of body resembling that in some of the Asco- myzontidas, being comparatively slender, with the anterior division moderately broad, and the cephalic segment scarcely projecting at the postero-lateral cor- ners. Tail rather produced and of quite normal appearance, being composed in female of 4, in male of 5 segments. Anterior antennas slender, with the number of joints somewhat reduced; terminal part not defined, the usual sesthetask issuing from the last joint, near the tip. Posterior antennae comparatively small, but with the terminal joint more developed than in the Aseomyzontidoe, outer ramus rudimentary. Oral cone more or less produced. Mandibles without any palp. Maxilla? and maxillipeds on the whole normal. Natatory legs resembling in structure those in the Ascomijzontidce. Last pair of legs with the proximal joint imperfectly defined from the segment, distal joint very small or of moderate size. Remark*. This is another family, which I have found it necessary to establish in order to include the 2 genera Myzoi>unlitt* and Xeupontius, the systematic position of which has appeared rather doubtful. Giesbrecht refers both these genera to his sub-f?mily Dyspontiince, apparently on account of the somewhat similar structure of the anterior antennas; but in other respects they differ very conspicuously from the true Dyspontiinm, both as regards the outward appearance of the body and the structural details, while on the other hand they exhibit, several 113 characters in common, as indicated in the above diagnosis. As the genus Myzopontius was the first established of the two, the name of the family must be derived from that genus. Gen. 2(i. MyzOpOJltiUS, Giesbrecht, 1895. Generic Characters. -Anterior division of body moderately dilated, with the cephalic segment comparatively large, and the epimeral parts of the trunk- segments only slightly angular. Tail slender, though not much elongated. Caudal rami moderately produced. Anterior antennae slender and only sparingly seti- i'erous; those in male distinctly hinged, and provided with supplementary sesthe- tasks. Posterior antennae likewise comparatively slender, with the penultimate joint well defined and the terminal joint rather elongated. Oral cone produced into a slender siphonal tube. Mandibles very narrow. Maxillse with the inner lobe shorter than the outer, and provided with only a single apical seta. Both pairs of maxillipeds very slender. Terminal joint of outer ramus in 1st pair of natatory legs with 3 setse inside; same joint in the 3 succeeding pairs with 5 seta3. Last pair of legs very small. Remarks. This genus was established in the year 1895 by Giesbrecht, to include a species found by him in the Bay of Naples. In the elaborate monograph of the Asteroclierldce by the same author, this genus was placed at the head of the sub-family Dyspontiince, and its differences from the more typical genera, showing an approach to the Axteroclwrimv (= Ascomyzontidw), were pointed out. The genus as yet only comprises a single species, to be described below. 64. Myzopontius pungens, Giesbr. (PI. LXVIII). Myzopontius pwigens, (iieslirecht, Asterocheridse, p. 106. PI. 1, tig. 6, PL mr;>.v. Brady, Monograph of British (.'oprpoda, Vol. Ill, p. 61, PI. X< Mil. fiys. 1 9. Syn: Artotrocjits orbicular'^, Brady & Eoberts. (not Boeck). Sormanni, Cairn (not Brady). V Bradypontius Canui, Giesbrodit. Specific Characters. Female. General form of body somewhat similar to that in Dysponfms striatus, the anterior division being rather expanded, with the greatest width almost equalling the length. Cephalic segment very large, occupying about half the total length, and having the free edges evenly arched, postero- lateral corners rather produced, frontal part rounded, without any dorsal crest. Epimeral lappets of the 3 succeeding segments well defined and pointing obliquely backwards; those of penultimate segment of same shape as the preceding ones, though 125 somewhat smaller. Tail -not attaining half the length of the anterior division; genital segment moderately dilated in its anterior part; anal segment exceeding in length the 2 preceding ones combined. Caudal rami rather produced, being more than twice as long as they are broad, and fully attaining the length of the anal segment; outermost seta not far from the apex and somewhat shorter than the innermost; the 2 middle setae of moderate length. Anterior antennae about half the length of the cephalic segment, and composed of 8 (or 9) joints, the 2nd being much the largest; terminal joint almost the length of the 2 preceding ones combined. Posterior antennae with the terminal joint longer than the penultimate one, middle apical seta of moderate length, the other 2 very small. Siphon rather slender, extending beyond the limits of the cephalic segment. Mandibles nairow styliform, and distinctly denticulated at the apex. Maxillae with the lobes com- paratively narrow and somewhat unequal in length, apical seta of the inner one quite short, those of the outer slender and subequal. Maxillipeds well developed, dactyl us of the anterior ones moderately slender, with a small secondary spine at some distance from the end; terminal claw comparatively short. 1st pair of natatory legs not much smaller than the 2 succeeding ones, seta at the inner corner of the 1st basal joint conspicuously thickened. 4th pair of legs with the inner ramus much narrower than the outer and only slightly exceeding in length the 2 first joints of this ramus combined, seta? present in the usual number, but rather reduced in size Free joint of last pair of legs small, and as in the other species provided with 3 bristles, the innermost one the longest. Ovisacs rather large and globular in form. Colour not yet ascertained. Length of adult female 1.80 mm. Male unknown. Remarlcs. I think I am right in identifying the above-described form with Brady's species, as it agrees fairly well in its outward appearance with the figure given by that author. The apparent differences found in some of the structural details may indeed be due to a less careful examination by the said author. It appears to me somewhat more doubtful, if the form described by Canu as Arto- trogus Normani, and subsequently named by Giesbrecht Bradypontius Caniii, is in reality identical with the present species, as set foith by the last-named author in his Monograph of the Asterocheridos j and the form briefly described and figured by .Giesbrecht in the same Monograph as B. mayniceps, also seems to differ in some respects. The present species was at first erroneously identified by Brady and Robertson with Artotrogus orbicularis Boeck; and though this mistake was sub- 126 sequently corrected, it was still referred by Brady in his Monograph to Boeck's genus, which in reality is so very different, that in my opinion it cannot even be included in the present family. Occurrence. Only a few female specimens of this form have hitherto come under my notice. They were taken free in the sea in two widely-distant localities, viz., at Aalesund, west coast of Norway, and at Hammerfest, western Finmark. Distribution. British Isles (Brady), ? coast of France (Canu). 70. Bradypontius papillatus (Scott). (PL LXXIV). Artotroyns paiiUlatus, Scott, Sixtli Annual Report of the Fishery Board for Scotland, Appendix. p. 232, PI. VIII, fiys. 712. Syn: Bradypontius iln'Ji /'/>-. (iiesbr. Specific Characters. Female. Anterior division of body rather broad in its posterior part, greatest width however not quite equalling the length. Cephalic segment very large, occupying more than half the total length, and gradually contracted anteriorly, postero-lateral corners very prominent, frontal part nar- rowly produced, with a very distinct crest running along its dorsal face; rostral projection well marked, incurved. Epimeral lappets of the 2 succeeding segments well developed and considerably divergent; those of penultimate segment, however, rather small and conically pointed. Tail only slightly exceeding in length Ya of the anterior division; genital segment moderately dilated in front; anal segment not attaining the length of the 2 preceding ones combined. Caudal rami about twice as long as they are broad, and equal in length to the anal segment; outer- most seta at some distance from the apex, and shorter than the innermost; the 2 middle setae of moderate size. Anterior antennae about half the length of the cephalic segment, and composed of 9 joints, 2nd joint the largest, terminal joint exceeding in length the 2 preceding joints combined. Posterior antennae resembling in structure those in B. magniceps, except that the outermost apical seta is com- paratively longer. Siphon scarcely extending beyond the insertion of the 1st pair of legs. Maxillae with the lobes less slender than in B. magniccp*, apical seta of the inner one short, those of outer lobe very coarse, spiniform, and finely denti- culated. Anterior maxillipeds with the dactylus rather strong and provided at some distance from the end with 2 small thumb-like prominences, against which the curved terminal claw may admit of being impinged; secondary spine very small and placed outside the said prominences. Posterior maxillipeds normal. Natatory legs resembling in structure those in B. magniceps, except that the inner 127 ramus in 4th pair is much smaller, scarcely attaining the length of the 2 first joints of the outer one combined, and very narrow, with some of the setae aborted. Last pair of legs about as in the preceding species. Colour dark yellow or orange. Length of adult female amounting to 1.60 mm. Remarks. I cannot doubt that the above-described form is that originally recorded by Scott as Artotrogus papillatus, and that Giesbrecht's Bradypontius chelifer is the same species. It is true, that the number of joints in the anterior antennae is indicated by both these authors to be only 8, and that the terminal part of the dactylus in the anterior maxillipeds is represented much shorter and thicker than in the specimen examined by me; but these apparent differences are in all probability due to the circumstance that the specimens examined by those authors had not arrived at full maturity, as proved by their much inferior size (1.15 1.20 mm.). In all other respects the agreement seems to be perfect. From the type species, B. magniceps, the present one is easily distinguished by the rather different form of the cephalic segment and of the epimeral lappets, as also by the comparatively shorter caudal rami. The very feeble development of the inner ramus on the 4th pair of legs forms another rather characteristic specific mark. Occurrence. Some few female specimens of this form were collected, many years ago, in 2 localities on the west coast of Norway, viz., at Aalesund and Eggesb0na3S. The specimens were taken free in the sea, at depths ranging from 20 to 40 fathoms. Distribution. British Isles (Scott), Bay of Naples (Giesbrecht). 71. Bradypontius major, G. 0. Sars, n. sp. (PI. LXXV). Specific Characters: Female. General form of body somewhat similar to that in B. papillatus, the cephalic segment being very large and gradually con- tracted anteriorly, with a well-marked dorsal crest running along its frontal part. Epimeral lappets of the 3 succeeding segments more closely crowded together and less unequal than in the said species; those of penultimate segment well developed, though somewhat narrower than the others. Tail comparatively short, only slightly exceeding in length l j- A of the anterior division; genital segment considerably dilated in its anterior part; anal segment equalling in length the 2 preceding ones combined. Caudal rami scarcely twice as long as they are broad, and shorter than the anal segment, apical setse about as in the preceding species. Anterior antennas not very elongated, but composed (in the specimen examined) of no less 128 than 13 well-defined joints, a short joint being divided off from the elongated 2nd joint both at the base and at the end, and moreover each of the 2 joints pre- ceding the terminal one being distinctly subdivided; terminal joint about the length of these 4 joints combined. Posterior antennae a little more slender than in B. papillatus. but otherwise of a very similar structure. Siphon rather produced, extending considerably beyond the limits of the cephalic segment. Mandibles very slender and distinctly denticulated at the tip. Maxillae with the lobes narrow and rather unequal in length; apical seta of the inner one much produced, those of the outer rather slender. Anterior maxillipeds with the dactylus much more slender than in B. papillatus, with only a single small thumb-like process rather far from the apex, secondary spine well marked. Natatory legs with the rami comparatively less slender than in that species; inner ramus of 4th pair more fully developed, exceeding in length the first 2 joints of the outer one combined. Free joint of last pair of legs a little larger than in B. papillatus. Male considerably smaller than female, and having the anterior division less expanded. Anterior antenna?, as in female, composed of 13 joints, 6th and 7th joints very short and less sharply defined, loth joint conspicuously dilated and armed anteriorly with 2 slender spines, movable terminal part distinctly biarticulate. Inner ramus of 4th pair of legs comparatively longer than in female, terminal joint produced at the outer distal corner to an outward-curving denti- form projection, outer apical seta, as also that of the outer edge replaced by a short club like spine. Body in female of a dark yellowish grey colour, and ornamented on the dorsal face with a reddish branching pigment. Length of adult female amounting to 2.40 mm., of male to 1.95 mm. Remarks. This form is closely allied to B, papillatus, but of much larger size, and moreover differs conspicuously in the shape of the epimeral lappets of the trunk-segments, as also in some of the structural details, as indicated in the above diagnosis. Occurrence. Solitary specimens of this large species have been taken at Aalesund, west coast of Norway, and in the Trondhjem Fjord, at R0dbjerget, in both localities from considerable depths. 72. Brady pontius caudatus, G. 0. Sars, n. sp. (PL LXXVI). Specific Characters. Female. Body comparatively more slender than in the other species, with the anterior division moderately expanded. Cephalic 129 segment large, though scarcely occupying half the total length, and only slightly contracted anteriorly, frontal crest only faintly indicated, postero-lateral corners of the segment fairly prominent. Epimeral lappets of the 3 succeeding seg- ments moderately produced ; those of penultimate segment rather smaller than the preceding ones. .Tail comparatively more produced than in the other species, attaining nearly half the length of the anterior division; genital segment not much expanded in its anterior part; anal segment scarcely as long as the 2 preceding ones combined. Caudal rami about twice as long as they are broad, and slightly dilated in the middle ; outermost seta rather far from the apex and much shorter than the innermost, the 2 middle setse of moderate length. Anterior antennae unusually slender and elongated, considerably exceeding half the length of the cephalic segment, and composed of 12 well-defined joints, the last of which is the longest. Posterior antennoe likewise rather slender, with the ter- minal joint nearly twice as long as the penultimate one. Siphon moderately produced, extending about to the insertion of the 1st pair of legs. Maxillae with the lobes not very unequal; apical seta of the inner one quite short, those of the outer very coarse, spiniform and densely spinulose. Maxillipeds resembling in structure those in B. major, the dactylus of the anterior ones being very slender, with only a single small thumb-like process at some distance from the end, terminal claw much curved, secondary spine small. Natatory legs rather strongly built, with the exterior edge of the outer ram us coarsely serrate; inner ramus of 4th pair not much shorter than the outer, but rather narrower. Free joint of last pair of legs somewhat more produced than in the other species. Colour reddish brown. Length of adult female reaching to 2.90 mm. Male unknown. 1 ) RemarJcs. This form grows to a still larger size than B. major, and is indeed the largest of all the siphonostomous Cyclopoida with which I am acquainted. It moreover exhibits several well-marked differences from the other species, both as to its outward appearance and the structural details. The specific name alludes to the unusually produced tail. Occurrence. 2 female specimens only of this form have come under my notice. They were taken, many years ago, at Tj0t0 on the Nordland coast, from the considerable depth of 150 fathoms *) It may be, however, that the male specimen mentioned above as belonging to B. major. should more properly be referred to the present species, though it was found in company with the former. Indeed, on a closer examination, I have found that the caudal rami in that specimen, as also the mutual relations of the joints in the inner ramus of the 4th pair of legs, agree better with the present species. 17 Crustacea. 130 Gen. 32. CrlbrOpOntiUS, Giesbr. 1899. Syn : Artotrogus, Brady (part). Generic Characters. Body robust, with strongly chitinised integuments, and with some of the epimeral lappets very prominent. Tail somewhat pro- duced and having the genital segment in female less expanded than in the other genera. Caudal rami lamellar, with comparatively short apical setae. Anterior antennae comparatively stout and scarcely at all attenuated distally. Posterior antennae with the terminal joint comparatively short. Siphon rather strong and not much produced. Maxillae with the lobes very unequal in size and each provided with 2 slender apical setae. Both pairs of maxillipeds, but especially the posterior ones, very powerfully developed. Natatory legs on the whole agreeing in structure with those in Bradypontiuv: inner ramus of 4th pair, as in that genus, distinctly 3-articulate. Last pair of legs somewhat more fully developed than in the other Dyspontiidce. Remarks. This genus, established by Giesbrecht, is allied to Brady - pont'ius, agreeing with it in the presence of a distinctly 3-articulate inner ramus on the 4th pair of legs. It differs however in some points rather conspicuously, both as regards the outward appearance and some of the structural details, and therefore ought evidently to be supported. We do not know at present more than a single species, to be described below. 73. Cribropontius Normani, (Brady). (PL I A XVII). Artotroyun Noniiani, Brady, Monograph of British Copepoda, Vol. Ill, p. <>3. PI X< T, figs. 1215, PL XCII, fig- 14, PL XGIII, fig. 10. Syii: Dyspontius Normani, Brady & Roberts. Bradypontius Normani. Giesbrecht. Specific Charactca of intestine very fully developed, extending along the sides of the cephalic segment and also penetrating into the adjacent part of the trunk, being divided outside into numerous narrow lobules. Ovisacs globular in form and wholly concealed beneath the posterior part of the trunk. Body of a light yellowish brown colour, with the intestine and its lateral co?ca of a darker hue; ova in the ovisacs orange-coloured. Length of adult female about 2 mm. Male (at least in its adult state) unknown. 1 ) Remarks. The present Copepod cannot be confounded with any of the other siphonostomous Cyclopoida, being clearly distinguished by the pronouncedly clypeiform shape of the body and its nearly circular form. It is however not improbable that the hitherto unknown female of Dystrogus will be found to approach nearer to Artotro