rom eae

% aleeatneacesncones mtbhetenepen, ate te [etalon eierets,

oem et >, wes ew oer e -

Bak aes

ek. Stee lnc toes 7

2 9995900 TOEO O

WOUANAUUGOAQUM

\OHM/1EWN

ae =a bad

SiN vane

a: hire a |

_ Proofsheet.

ey ACCOUNT

OF THE

me STACKAS

OF

NORWAY

WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES

j

Ps et Ke Zz Y

BY

GO SARS

PROFESSOR AT THE UNIVERSITY OF CRISTIANIA.

Vol I—1 AMPHIPODA

CHRISTIANIA AND COPENHAGEN ALB. CAMMERMEYERS FORLAG PRINTING OFFICE OF MALLING 1893

es ZX = © © © < Z, ae

%

OF THE

OF

e

2}

aeoN ACCOUNT

OF THE

BUSTACEA

OF

NORWAY

WITH SHORT DESCRIPTIONS AND FIGURES OF ALL THE SPECIES

BY

GeO. Saks

PROFESSOR AT THE UNIVERSITY OF CHRISTIANIA

Vol I.

ROWE? Feel PAB).

(RE Ds)

CHRISTIANIA AND COPENHAGEN ALB. CAMMERMEYERS FORLAG

(LARS SWANST

1995

Ro i,

¢! iJ

ws

A. as ett:

> a

PREFACE.

In presenting to the scientific world the 1st Volume of the great work on Norwegian Crustacea, which I have entered upon, I wish to make the following observations about the plan of the work in general, and especi- ally that of the present Volume.

The author, who during a long series of years has been engaged by the government to make investigations about the sea-fisheries of Norway, and for this purpose has made numerous journeys of research along the whole Norwegian coast, from the Christianiafjord to WVadso, has thereby had an unusually convenient opportunity for at the same time studying the rich marine invertebrate fauna occurring along that extensive coast, and has especially made himself familiar with the several groups of Crustacea, which had long before been his special study. A very large amount of zoological material has thus from time to time been brought together from many different localities, and among this material have been found numerous interesting forms new to science. Most of the new Crustacea have been briefly characterised by the author in several papers, chiefly published in the Transactions of the Scientific Society of Christiania, and a few groups, for instance the Myside, have also been more fully treated of in separate treatises. It has, however, appeared to the author very desirable, that a full account of the rich caret nological fauna of Norway should be given, like that of the British Crustacea long ago published by several distinguished carcilogists, both because such faunistic works have on the whole shown themselves to be extremely useful, and because the fauna of Norway, as is well known, belongs to two distinct zoological regions, the boreal and arctic, and thus exhibits characteristic differ- ences from that of the British Isles. Indeed, the author has long felt it as a veritable duty, by entering upon a such work, to utilise his long experience for the benefit of future carcinologists. But the great expenses connected with the publication of such an extensive work in the usual manner, as publication from the University, have hitherto prevented him from realizing his plan, and

it is only some few years since the idea struck him to get the work published

VI

in the mode here adopted. By reducing the expenses of publication as far as possible, and inviting to a general subscription, I supposed indeed that the publication of the work could be carried on by one of our publishing firms, without any real pecuniary loss, and by this means I have now the satisfaction of seeing the 1st Volume of my work accomplished. I cannot of course expect to be enabled during the remainder of my life to bring to a conclusion a work of such an extent as that now entered upon, comprising, as it does, the whole rich carcinological fauna of Norway, but I venture to hope that my health and working power will at least suffice for accomplishing a part of this formidable work. If the volume now published should succeed in gaining the interest of Norwegian and foreign zoologists, and the anticipation entertained in beginning the work should thus be confirmed, it is my intention immediately to enter upon the publication of the 2nd Volume, treating of the next order, the Lsopoda.

As to the Volume now accomplished, it has been wholly devoted to the extensive order of the Amphipoda, one of the most difficult of the Crus- tacean groups. The chief earlier investigation of the Norwegian Amphipoda is due to the late Dr. Axel Boeck, who at first published a brief account in Latin, and subsequently began the elaboration of his well-known great work, containing full descriptions of the species, and accompanied by numerous litho- eraphic plates. Unfortunately he himself only published a comparatively small part of this work, the remainding, far greater part being published after his lamented death by his brother, Dr. Hakon Boeck, who was not originally a zoologist, but yet endeavoured to arrange the scattered, posthumous manuscript notes and drawings for the completion of the work. Although the great skill, with which this very difficult undertaking was accomplished, deserves the highest admiration, it was of course unavoidable, that several grave errors were incorporated in the work, which otherwise should have been eliminated. As moreover, in order to get room on the plates for the numerous figures, a most regrettable reduction in size of the original drawings was effected, and some of the figures also wrongly numbered, several of the species had in some cases become almost unrecognizable. For these reasons the work of Boeck, though enriching the fauna with an immense number of new and interesting forms, could not be used without the greatest precaution and critical judgement, and rendered in fact the study of the Norwegian Amphipoda extremely difficult and troublesome. Notwithstanding this, some parts of the Amphipodous fauna were subsequently treated of in detail by Mr. Schneider, and a.most valuable account of the arctic species of the family Oediceride, accompanied by some very good and sufficiently large detail-figures, has been

given by that distinguished zoologist. But otherwise the knowledge of the

VII

Norwegian Amphipoda was still restricted to Boeck’s work, the use of which was, as above stated, connected with very much difficulty. Under such circumstances, I thought it right in the first instance to enter upon a_ total revision of this order, hoping thereby to supply the above-mentioned wants in Boeck’s work. To this end, I have gone over the vast collection of Amphi- -poda made by Boeck, and especially most carefully examined the several type specimens in the collection, whereby several difficult questions about the right identification of the Boeckian species have been finally settled. Nearly all the species described in the said work have been subsequently found by myself, and in most cases examined in the living state, and numerous additional species have been procured, increasing the number of Norwegian forms to about 400 in all.

The aim of the present Volume is chiefly to facilitate the determina- tion of the northern Amphipoda. This, I believe, may be best attained, not only by giving good and concise diagnoses of the species, but especially by supplying figures, true to nature, and of sufficient size and clearness, both of the entire animal and of the most characteristic anatomical details. The lack of good figures has indeed hitherto made the study of this interesting order of Crustacea very difficult and, in- many cases, has caused sad confusion in the synonymy. Very great care has therefore been paid to the preparation of the plates accompanying this Volume. They have been all drawn by the author himself, by the authographic method applied by him very successfully during a series of years, and the habitus-figures have, in nearly every case, been copied from carefully executed, coloured drawings made by the author from living specimens, thus showing the mode of pigmentation characteristic to each species. In every generic type the structure of the oral parts has been carefully examined, and figures of the same given on a greatly enlarged scale, as the classification of the Amphipoda ought chiefly to be based upon this character.

As to the systematical arrangement of the Amphipoda, I have only made some few changes in the system adopted by Boeck. It is, however, most probable, that a somewhat altered arrangement may be found convenient in future, as some of the families are far from being well defined.

In the Appendix to the volume some additions and corrections have been given, and some new species described and figured.

During the elaboration of the work, I have had very important assistance in the excellent Report of the «Challenger» Amphipoda by the Rev. Mr. Stebbing, the very complete and elaborated survey of the literature given in that; Report having especially been most invaluable to me.

I regret not having had an opportunity of consulting the recently

Ln

published work of Delle Valle on the Amphipoda of the gulf of Naples. It is most likely that some interesting statements about the geographical distri- bution of the northern species are to be drawn from this work.

For the exact identification and comparison of arctic species, I am much indebted to Dr. Hansen, who with great liberality has sent me for examination several of the type specimens originally examined by Kroyer, and preserved in the Museum of Copenhagen, as also many other interesting arctic forms described by himself.

I have also to thank the Rev. Mr. Stebbing, Mr. Walker, the Rev. Mr. Norman, Mr. Chevreux, Mr. Schneider, and several other distinguished zoologists for kindly sending me Amphipoda for examination and determination.

My best thanks are also due to the publisher for the readiness with which he has untertaken the publication of such a large work, and for the beautiful manner in which the present Volume has been mounted, both as to type and paper.

October 1894.

G. O. Sars.

AMPHIPODA.

Terminology.

(Sees Bia)

Divisions of Body: C. Cephalon Ms. Mesosome

Mts Metasome | Posterior Division. Us. Urosome j}

Anterior Division.

Appendages of Cephalon:

al Superior antenne (peduncle, flagellum, secondary appendage).

a’. Inferior antennz (basal joint (b), olfactory spine (ol), peduncle, flagellum). L. Anterior lip (buccal plate, epistome).

l. Posterior lip (lobes, lateral corners).

M. Mandibles (body (b), masticatory part, cutting edge (c), molar expansion (m), palp (p)). First pair of maxillee (basal part (b), basal | Buccal: lobe (1'), masticatory lobe (1?), palp (p)). { m*. Second pair of maxille (basal part, inner and |

outer lobes). mp. Maxillipeds (basal part (b), basal lobes (1'),

masticatory lobes (1”), palp (p)).

(Eyes. Rostrum, Lateral corners).

Appendages of Mesosome: pe First pair of legs, or anterior gnathopoda. p”. Second pair of legs, or posterior gnathopoda. p’—p’. Third to seventh pairs of legs, or first to fifth pairs of pereiopoda. Joints in all the legs: 1. coxal, 2. basal, 3. ischial, 4. meral, 5. carpal, 6 propodal, 7. terminal, or dactylus. Appendages to the legs: br. branchial lamella, i. incubatory lamella.

!) The same lettering is used in all the plates to designate the corresponding parts,

Appendages of Metasome: pl'.—pl*. First to third pairs of pleopoda (basal part (b), rami (7)). (ep'.—ep*. First to third pairs of epimeral plates).

Appendages of Urosome:

up'.—up*. First to third pairs of uropoda (basal part, rami). t. Telson.

g Female, Go Male, of jr. Young male, Gt + nearly adult male.

ebead.

HYPERUDEA.

Body short and tumid, or very slender, with thin and pellucid integu- ments. Cephalon generally large and tumid; mesosome more or less abbreviated, with the coxal plates small and subequal in size; metasome powerfully developed, compressed, with large epimeral plates; urosome depressed, with the 2 outer seg- ments eoalesced. Eyes generally enormously developed. Antenne often imper- fect in female, superior ones without any secondary appendage (excepting the genus Hyperiopsis). Oral parts of various structure; maxillipeds without palps, basal lobes coalesced, masticatory lobes divergent, flap-shaped. Gnathopoda not very strong, subsimilar in the two sexes. Pereiopoda of various structure, some- times very dissimilar. Pleopoda powerfully developed. Uropoda more or less laminar, outer ramus of last pair without any terminal joint. Telson simple. Parasitic on pelagic animals, especially Meduse.

Remarks. This is a rather anomalous division of the Amphipoda, which by most authors has been placed at the close of the order. 1 think, however, it will be more appropriate to follow Boeck in treating of the present group at the head of the order, placing the typical Amphipoda (Gammaridea) in the midst between this tribe and that of the Caprellidea, the latter constituting a far more distinctly degradated type.

Fam. 1. Hyperiide.

Cephalon large and deep, almost globular. Eyes occupying the entire lateral walls of the head, visual elements very numerous and elongated, radiat- ing from a central pigmentary mass. Both pairs of antenne with distinctly triarticulate peduncles, the inferior ones originating each from a large and immobile basal joint, flagellum of both pairs in female comparatively short and non-articulated, in male very slender and elongated, multiarticulate. Ep1- stome not projecting. Anterior lip with a large bilobed buccal plate covering

the cutting edges of the mandibles. Posterior lip with the lobes subpedi- cellated and wide apart. Mandibles rather powerful, with the cutting edge finely denticulated, molar expansion more or less laminar, palp distinct, triarti- culate and naked. First pair of maxille without any basal lobe, masticatory lobe densely hairy and having a few slender terminal spines, palp lamellar, uniarticulate. Second pair of maxille with both lobes densely hairy and ter- minating in blunt points. Maxillipeds with the terminal lobes more or less erescent-like. Gnathopoda imperfectly subchelate, os complexly chelate. Pereio- poda generally not very dissimilar, basal jomt of the 3 posterior pairs rather narrow. Incubatory lamelle without marginal sete. Uropoda normal, biramous, rami lanceolate, without spines, but with the edges finely serrated. Telson triangular.

Remarks. Besides the 4 genera treated of in the following pages and belonging to the Norwegian fauna, Dr. Bovallius enumerates, in his «Systematical list of the Hyperiidea», 5 other exotic genera comprised in the same family, viz., Iuwlopis Bovall., Tawria Dana, Hyperiella Bovall., Themistella Bovall., and Phronimopsis Claus. Of the several characters distinguishing the family, the structure of the antenne in the 2 sexes may be named as the most easily recognisable one. Moreover the form of the cephalon and the structure of- the oral parts, partly also that of the pereiopoda, “afford well marked differences between this and the other Hyperidean families.

Gen 1. Hyperia, Latreille, 1825. Syn: Lestrigonus, M—Edwards = &.

Cephalon much more deep than long, somewhat flattened in front. Meso- some greatly inflated in the female, with the back evenly vaulted. Antenne in female very small, subequal. Mandibles with the molar expansion large and finely fluted transversally, palp of moderate size, with the 2 outer joints subequal in length. First pair of maxilla with the palp not very expanded, inner corner produced to a tooth-like projection. Maxillipeds with the ter- minal lobes obtusely pointed, inner edge with small tufts of hair. Gnathopoda searcely chelate; carpal joint, however, more or less produced inferiorly, especially in the posterior ones. Pereiopoda comparatively short and robust, subequal in length. Uropoda rather broad, with the rami foliaceous. Telson comparatively large.

Remarks. This genus, which may be considered the type of the family, comprises several species occurring in different parts of the Oceans. Dr. Bovallius enumerates 10 different species, two of which only belong to the Norwegian fauna,

1. Hyperia galba (Mont). (PIS 2) Pl. 3, fies): Cancer gammarus galba, Montagu, Linn. Transact. XI, p. 4, Die 2 dicen: Syn: Hyperia Latreilli,.M. Edw., « Lestrigonus exulans, Kréyer = ¢, « Hyperia medusarum, Boeck.

Body of female short and stout, with greatly dilated mesosome, of male considerably more slender and having the metasome much larger than in female. HEye-pigment very narrow reniform, reddish brown. Gnathopoda rather small and only sparingly bristle-beset, carpal joint in both pairs pro- duced, forming in the 2nd pair a narrow process reaching beyond the middle of the propodal joint; the latter attenuated and finely serrated along the inner edge; dactylus of both pairs rather slender and finely denticulated. Pereio- poda almost quite naked. Last pair of uropoda shorter than the urosome, rather broad, especially in the male. Colour pale purplish yellow. Length of female 14 mm, of male 12 mm. Maximum length of arctic specimens, according to Bovallius, 20 mm.

Remarks. In spite of the opinion supported by Dr. Bovallius, I cannot but believe Hyperia Latreilli of M. Edwards to be identical with H. galba Mont. The said author, it is true, enumerates some minor differences between the two; but none of them can in my opinion be regarded as strictly specific in character. It may moreover be observed, that the figures he gives of H. Latreilli are from a not yet fully adult male, whereas those of H. galba are from a quite adult specimen.

Occurrence. Rather common along the whole coast of Norway, found parasitic on Aelia, often several specimens, males, females and young ones on each Medusa.

Distribution. Atlantic coasts of France and Britain, the Cattegat, the Baltic, Arctic Ocean: Greenland, Spitsbergen, Novaja Semlja, Kara Sea,

the Murman coast.

2. Hyperia medusarum, (Miiller). (Pl. 3, fig. 2). Cancer medusarum, O. Fr. Miller, Zool. dan. prodromus, 2355, p. 148. Syn: Hyperia spinipes, Boeck.

In general habitus very like the preceding species. Kye-pigment however, somewhat larger and broader. Antenna very small in the female. Gnathopoda considerably larger than in H. galba and densely hirsute in their outer part, carpal joint scarcely at all produced in the Ist pair, and but very slightly

? t 2 v

so in the 2nd, propodal joint in both pairs oval in form, scarcely serrate along the inner edge, but all over densely spinous, dactylus very small. The 2 anterior pairs of pereiopoda having fascicles of short bristles along the posterior edge. Urepoda almost exactly asin H. galba. Colour dark purplish brown from numerous pigmentary spots distributed over the whole body as also on the limbs. Length of adult female 15 mm.

Remarks. I think Dr. Bovallius is right in believing the form described by Boeck under the name of Hyperia spinipes to be most likely identical with the Cancer medusarum of O. Fr. Miiller, and hence the latter specific denomination ought to be retained for the present form. Although in its general habitus very like the preceding species, this form may at once be distinguished, on closer examination, by the rather different form and armature of the gnathopoda, a character which suggested the specific name of spinipes proposed by Boeck.

Occurrence. West coast of Norway, found parasitic on Cyanea, occasionally also on Awrelia, but less frequently than the preceding species.

Distribution. Arctic Ocean: Greenland and Spitsbergen.

Gen. 2. Hyperoche, Bovallius, 1887.

Syn: Metoecus Kréyer, Tawria Boeck.

Form of body about as in Hyperia, but with the cephalon somewhat more regularly rounded. Inferior antenne in female much smaller than the superior ones; both pairs in male greatly elongated. Mandibles with the molar expansion narrow lanceolate and unarmed. First pair of maxille having the palp very broad and lamellar. Gnathopoda subsimilar, both distinctly chelate, the carpal jot being produced inferiorly to a compressed knife-like process reaching to the end of, or beyond, the propodal joint, and having the inner edge finely serrate; propodal joint narrow, attenuated, with the inner edge serrate; dactylus rather short. The two anterior pairs of pereio- poda having the carpal joint slightly expanded and compressed; posterior pairs subequal. Uropoda and telson about as in Hyperia.

Remarks. The generic name Metoecus of Kriéyer having been em- ployed in Zoology at an earlier date, Dr. Bovallius has proposed a new generic denomination, viz., Hyperoche. The same author has likewise shown that the northern form cannot properly be referred to the genus Tawria of Dana, as suggested by* Boeck. The genus is easily recognised by the peculiar structure of the gnathopoda. Otherwise it comes rather near to Hyperia, though differig also somewhat in the structure of the oral parts. Dr. Bo-

9 vallius enumerates 5 species of the present genus; but I regard the validity of some of these species rather doubtful. Thus I believe that only a sinele P 5 species is represented in the northern seas, instead of 3, as suggested by

that author.

3. Hyperoche Kroyeri, Bovallius. (Pl. 4). Metoecus medusarum, Kroyer, Gronlands Amphipoder. Danske Vid. Selsk. Afhandl. VALI pa ZS88se plans ation alin: Syn: Tauria abyssorum, Boeck. Hyperoche Liitkent, Bovall.

Body of female short and tumid, of male much more slender and compressed. Cephalon rounded in front, eye-pigment triangular. Mesosome with the back rather vaulted; metasome comparatively slender, with the epimeral plates not very large in female. Gnathopoda almost naked, carpal process of both pairs in female advancing beyond the propodal joint, in male somewhat shorter and narrower. Carpal joint of the 2 anterior pairs of pereiopoda having the posterior edge sharpened and minutely denticulated, terminating with a short triangular process; the 3 posterior pairs comparatively short and almost quite naked, with the basal joint rather narrow. Last pair of uropoda with the basal part about twice the length of the telson, in male rather broader than in female. Colour of female light reddish brown, of male more greyish, from numerous dark pigmentary spots. Usual length 5—6 mm. Maximum length of arctic specimens 15 mm.

Remarks. I believe that Dr. Bovallius is right in rejecting the specific name medusarum appled to this species by Kroyer, since the form designated by O. Fabricius as Oniscus medusarum in all probability was a true Hyperia and most likely the species described above as Hyperia me- dusarum. On the other hand I cannot coincide with that author in regarding Kréyer’s species distinct from Tauria abyssorum of Boeck. Nor can I doubt that Dr. Hansen is right in withdrawing the species established by the same author under the name of Hyperoche Liitkeni, as synonymous with the typical species described by Kroyer.

Occurrence. 1 have met with this form both off the south and west coasts of Norway up to Lofoten, at times near the surface of the sea, at times in greater depths, but always free, not parasitic. No doubt, however, that if in reality leads a parasitic life on Meduse or some other pelagic animals, as with the species of Hyperia.

Distribution. Arctic Ocean: Greenland, Labrador, Spitsbergen, the

White Sea, the Siberian Polar Sea.

tw

10

Gen. 3. Parathemisto, Boeck, 1870.

Body somewhat compressed, but with the back scarcely carinated. Cephalon irregularly rounded; mesosome moderately vaulted; metasome well developed, with large epimeral plates. Antenne in female subequal, more elongated than in the preceding genera; in male about as in Hyperia. Anterior lip with a large unequally bilobed buccal plate; posterior lip with the lobes densely ciliated, lateral corners produced. Mandibles rather strong, cutting edge very broad and minutely denticulated, molar expansion rather large, regularly serrate on the edge, palp with the middle joint very elongated. First pair of maxille with the palp rather expanded, inner edge denticulated and terminating with a small tooth-like projection. Terminal lobes of the maxillipeds acuminated and beset with scattered long sete. (Gnathopoda densely hirsute and rather dissimilar; 1st pair simple, with the carpal joint rather broad and not produced inferiorly; 2nd pair subchelate, the carpal joint being produced to a narrow process, which does not, however, reach the end of the propodal joint; dactylus of both pairs rather elongated. The 2 anterior pairs of pereiopoda having the carpal joint only slightly dilated; the 3 posterior pairs very slender, subequal, with the carpal and propodal joints, especially the latter, greatly elongated and almost naked. Uropoda more slender than in the preceding genera. Telson comparatively small.

Remarks. This genus, established by Boeck, is very nearly related to the succeeding one, Huthemisto, and ought perhaps to be combined with it. The distinctive characters are chiefly the equal-sized antenne of the female, the less powerful structure of the 2 anterior pairs of pereiopoda and the uniform development of the 3 posterior ones. Besides the northern species described below, the Hyperia trigona of Dana would seem to belong to this genus, as also 2 new species described, the one by Bovallius, the other by the Rev. Stebbing.

4. Parathemisto oblivia, (Kroyer). (Pl 5, fig 1). Hyperia oblivia, Kroyer, Gronlands Amphipoder, 1 e¢. p. 70, pl. 4, fig. 19. Syn: Parathemisto abyssorum, Boeck.

Body moderately slender, with the Ist segment of the mesosome much longer than the 2nd. Cephalon rather large, only slightly more deep than long; eye-pigment oval, very dark. Superior antenne in female about as long as the cephalon and the Ist segment of the mesosome combined, flagellum only very slightly curved, about three times the length of the peduncle. Gnatho- poda with the propodal joint about as long as the carpal one; carpal process

of 2nd pair very narrow, reaching beyond the middle of the propodal joint:

11

dactylus very slender. Carpal joint of the 2 anterior pairs of perelopoda oblong, with 3—4 slender sete on the posterior edge. Propodal joint of the 3 posterior pairs very slender, nearly as long as the 3 preceding joints com- bined; dactylus narrow and elongated. Last pair of uropoda with the basal part about as long as the urosome, inner ramus slightly larger than the outer and about half the length of the basal part. Body pellucid with dark purplish intestine and scattered pigmentary spots of same colour. Usual length 10 mm. Maximum length of arctic specimens 17 mm.

Remarks. -— Although the description and figures given by Kroyer of his Hyperia oblivia are rather incomplete, I cannot doubt that they refer to the present species, which moreover is stated by Dr. Hansen to occur off the coast of Greenland, whence Kréyer procured his specimens. .From P. trigona of Dana it would seem to differ, among other characters, by the much more slender and narrow form of the propodal joint of the 3 posterior pairs of pereiopoda.

Occurrence. I have repeatedly taken this form in great number on the west coast of Norway up to Finmark, and generally in great depths, from 100 to 200 fathoms. A much smaller form, scarcely exceeding ) mm in length but otherwise wholly agreeing with the typical species, I have met with in less depth and occasionally even near the surface of the sea. On the other hand specimens collected on the Norwegian North-Atlantic Ex- pedition reach the considerable length of 17 mm. All the specimens were taken either by the dredge or by a surface-net fixed to the dredge-rope.

Distribution. British Islands (Sp. Bate), south coast of Green- land (Kroyer, Hansen), several Stations of the Norwegian North-Atlantic Kx- pedition from Lat. 63° to 71° (off Jan Mayen).

Gen. 4. Kuthemisto, Bovallius, 1887. Syn: Themisto, Guérin, 1828.

Body very slender and compressed, often distinctly carmated dorsally. Cephalon irregularly rounded. Superior antenne in female shorter than the inferior ones and having the flagellum more or less curved. Oral parts almost exactly as in Parathemisto. Gnathopoda likewise of a very similar structure, but the carpal process of the 2nd pair generally larger, and the dactylus shorter. The two anterior pairs of pereiopoda rather powerful, with the carpal joint greatly dilated, propodal joint slender and admitting of being

12

bent in against the former. Third pair of pereiopoda greatly produced and generally much longer than the 2 succeeding pairs, having the carpal and propodal joints very elongated and the latter often peculiarly denticulated, whereas the meral joint is much abbreviated. Uropoda rather slender. Telson small, triangular.

Remarks. As mentioned above, this genus is very nearly related to the preceding one, scarcely differing except in the mutual longitudinal relation of the pereiopoda and in the powerful structure of the 2 anterior pairs. The usual known generic denomination, Themisto, has been changed by Dr. Bovallius to Enthemisto, because the former name was employed in Zoology anterior to 1828. The genus is represented both in the antarctic and arctic Oceans. Dr. Bovallius enumerates 6 species, one of which, however E. Nordenskjoldi Bovall., has been withdrawn by Dr. Hansen as most probably only founded on immature specimens of J. libellula, (Mandt). No less than 3

different species belong to the Norwegian fauna.

5. Euthemisto compressa, ((roés). (Pl. 5, fig. 2). Themisto compressa, Goés, Ofvers. af Kgl. Svenska Vetensk. Akad. forhandl. 1865, p. 538, pl. 41, fig. 34. Syn: ? Huthemisto bispinosa, Bovall., not Boeck.

Body moderately slender and highly compressed, back distinctly earinated and forming on the posterior segments of the mesosome and _ the anterior ones of the metasome sharp recurved processes. Cephalon, as seen laterally, rounded triangular, more deep than long; eye-pigment of moderate size, oval. Superior antenne in female about the length of the cephalon, flagellum strongly curved and denticulated on the posterior edge. Posterior gnathopoda with the carpal process almost reaching the tip of the propodal joint, dactylus searcely more than half the length of the latter jomt. Carpal joint of the 2 anterior pairs of pereiopoda regularly oval, broadest in the middle, with rather short and unequal bristles on the posterior edge. Third pair of pereio- poda only shghtly exceeding in length the 2 sueceding ones, basal joint not expanded, propodal joint very slender and about the length of the 3 preceding joints combined, anterior edge very minutely denticulated throughout and provided at regular intervals with about 10 slender bristles; dactylus rather elongate, unarmed. Posterior pair of uropoda nearly twice the length of the urosome, outer ramus much shorter than inner. Body pellucid, with dark intestine and scattered purplish pigmentary spots on the posterior division of the body. Usual length 12 mm. Maximum length of arctic specimens,

according to Bovallius, 80 mm. (?).

Remarks. Boeck has referred this form to the genus Parathemisto, because in the figure given by Goés the 3 posterior pairs of pereiopoda are represented as being of uniform length. In reality, however, the 3d pair are, at least in full-grown specimens, distinctly longer than the 2 sueceeding ones, although the difference in this species is not nearly so great as in the 2 succeeding species. Moreover the powerful structure of the 2 anterior pairs of pereiopoda, as also the mutual length of the antenne, shows this form to be a true Huthemisto. As to the form named by Dr. Bovallius FZ. bispinosa Boeck, at least the habitus-figure given would seem more properly to relate to the present than to Boeck’s species.

Occurrence. Off the coast of Norway I have only observed this form in a single locality, viz., at Hasvig in west Finmark. It occurred here rather sparingly in deep water together with Parathemisto oblivia.

Distribution. Arctic Ocean: Davis strait, east coast of Greenland, Jan Mayen at Stat. 225 of the Norwegian North Atlantic Expedition.

6. Euthemisto libellula, (Mandt). Gal @, aie 1),

Gammarus libellula, Mandt, Observationes in Historiam naturalem et Anatomiam comparatam in itinere gronlandico facts, p. 32.

Syn: Themisto arctica, Kroyer.

Body very slender, with the back rounded, not earinated. Cephalon scarcely more deep than long, obliquely rounded in front; eye-pigment rather large, obliquely oval. Superior antenne with the flagellum scarcely curved. Gnathopoda having the propodal joint shorter than the carpal one, carpal process of the 2nd pair nearly reaching the tip of the propodal joint, dactylus very small. Carpal joint of the 2 anterior pairs of pereiopoda broadly ovate, slightly expanded towards the extremity and provided, on the posterior edge, with a regular series of rather elongated seta. Third pair of pereiopoda very elongated, basal joint expanded, with the anterior edge bulging out on the middle and provided with short bristles, propodal joint about the length of the carpal, anterior edge with a regular series of rather strong sete placed at regular intervals and increasing in length towards the extremity, outer part of the edge densely spinulous, dactylus slightly flexuous, with a dense tuft of fine spinules at the base. Urosome very slender, about half the length of the metasome. Uropoda likewise very slender, rami of the last pair

subequal in length. Body densely ornamented with dark purplish pigmentary

14

spots, intestine dark bluish. Length of adult specimens 45 mm. Maximum length of arctic specimens, according to Bovallius, 60 mm.

Remarks. This gigantic species is easily distinguished from the two other northern forms by the rounded, not carinated, back, the very slender urosome, and by the dactyli of the pereiopoda, especially those of the 3d pair, being densely spinulous at the base. In all these points the form named by Bovallius FE. Nordenskjoldi agrees with the present species, from which it can hardly be specifically distinguished.

Occurrence. Occasionally this form may be found in large shoals at the north and east coast of Finmark, swimming near the surface of the sea; but generally only young specimens are met with. The figure here given is from a specimen procured on the Norwegian North Atlantic Expedition.

Distribution. Arctic Ocean, widely distributed: Greenland, Spits- bergen, Jan Mayen, Novaja Semlja, Siberian Polar Sea, numerons_ stations of the Norwegian North-Atlantic Expedition, both in deep water and at the surface of the sea.

~~

(. Euthemisto bispinosa, (Boeck).

(Pl. 6, fig. 2).

Themisto bispinosa, Boeck, Crust. Amphip. borealia et arctica, p. 8.

Body rather slender, with the back carinated, the 2 last segments of the mesosome forming distinct retrovergent dorsal processes. Cephalon nearly twice as deep as long, obtusely truncated in front; eye-pigment rather narrow, almost crescent-like. Superior antenne scarcely longer than the cephalon, flagellum minutely denticulated on the posterior edge and having the extremity distinctly curved. Posterior gnathopoda with the carpal process not nearly reaching the tip of the propodal joint; dactylus comparatively small. Carpal joint of the 2 anterior pairs of pereiopoda irregularly ovate, somewhat tapering in the outer part and fringed with comparatively short and unequal bristles. Third pair of pereiopoda exceedingly elongate and slender, basal joint less expanded than in FE. libellula, propodal joint very narrow, much longer than the carpal joint and quite straight, anterior edge with only a few small setee in the middle, outer part regularly pectinate, the spinules gradually increasing in length towards the tip of the jot; dactylus very small and unarmed. Last pair of uropoda about twiee the length of the urosome, outer ramus much smaller than inner. Telson rather small. Body pellucid, with dark purplish intestine, and ornamented with scattered stellate

pigmentary spots, especially on the posterior division. Length of adult

15

specimens 15 mm. Maximum length of arctic specimens, according to Boeck 25 mm.

Remarks. In some characteristics, e. g., in the carinated hack and the structure of the antenne, this species shows a perplexing resemblance to I. compressa (Goés), and on this account the two species would seem to have been confounded both by Boeck and Bovallius. On closer examination, the present species is, however, easily distinguished by the exceedingly elongate and slender form of the 3rd pair of pereiopoda, and more especially by the peculiar armature of the propodal joint of these legs. It may be observed that this character is also quite distinct in very young specimens, whereas in these the dorsal processes are very inconspicuous or nearly quite obsolete.

Occurrence. Of this form I have taken a few adult and several young specimens at Sorver and Hasvig in west Finmark, together with Ei. compressa and Parathemisto oblivia.

Distribution. Arctic Ocean: Greenland, Spitsbergen (?); off Nova Scotia (Stebbing).

Fam. 2. Lyceide.

Cephalon large, subglobular, canaliculated inferiorly. Eyes enormous, occupying the entire lateral walls of the head. Antenne originating from the inferior side of the cephalon, very dissimilar; 1st pair rather small, with short uniarticulated peduncle (in female), flagellum rather dissimilar in the two sexes; 2nd pair imperfectly developed in female, very large in male and folded up beneath the cephalon. Oral parts more or less imperfectly developed. Gnatho- poda simple, or complexly subchelate. The 3 posterior pair of pereiopoda with the basal joint more or less expanded, last pair generally very small. Incubatory lamellee without marginal sete. Pleopoda very powerful. Uropoda normal. Telson triangular.

Remarks. This family is synonymous with the family Tryphanida of Boeck and Bovallius. I have, however, seen fit to change the name, f a family

because, according to the rules of Zoology, the denomination ¢ ought to be derived from the genus first established, and as the genus Lycwa of Dana undoubtedly belong to the same family as the genus T7'ryphana of Boeck, the family must of course be named after the former genus, which is by far the older one. According to the restrictions of Dr. Bovallius, the

family comprises, besides the 2 above mentioned genera, 5 others, viz.,

16 Thamyris Sp. Bate, Thamneus Bovall., Paralycea Claus, Pseudolycea Claus and Simorhynchus Claus. The family is mainly represented in the tropical part of the Oceans, the genus Tryphena being the only northern representative.

Gen. 5. Trypheena, Boeck, 1870.

Body comparatively short and stout, with rounded, not carinated back. Cephalon much deeper than the body, slightly produced in front, inferior side deeply canaliculated. Mesosome more or less abbreviated, metasome greatly developed, urosome comparatively short and depressed. First pair of antennee originating from the inferior side of the head in front, and admitting of being reflexed within the deep ventral furrow; flagellum triarticulate, Ist joint in female rather short, in male globularly expanded and bearing a dense tuft of sensory hairs at the posterior edge, 2nd joint linear with a few sensory appendages near the tip, in male rather narrow and produced inferiorly to a spiniform process, last joint in both sexes narrow styliform. Second pair of antenne fixed, at a great distance from the Ist pair, to the infero-lateral corners of the cephalon; in female very small and immobile, triarticulate, 2nd joint laminar, terminal one minute, scale-like; in male very large, peduncle 4articulate, the 2 outer joints slender and angularly bent, flagellum very narrow filiform, indistinctly articulate and likewise angularly bent. Anterior lip triangular, with a very short, slightly emarginated buccal plate; posterior lip wanting. Mandibles without any molar expansion, palp naked, biarticulate (in female). Both pairs of maxille forming simple narrow plates without any armature. Maxillipeds large, operculiform; terminal lobes short and_ broad, crescent-like, unarmed. Gnathopoda small, not chelate; Ist pair with the basal joint very large, lamellar, dactylus spiniform, immobile; 2nd pair rather slender, dactylus densely hairy and terminating with a kind of sensory apparatus (?). Pereiopoda almost naked, 3rd pair the largest, last pair very small. Uropoda comparatively short, with broadly louceolate rami. Telson large, triangular.

Remarks. Owing to the generally very imperfect investigation of Hyperids by Dana and earlier authors, Boeck has failed to recognise the near relationship of his genus Tryphena to the genus Lycwa of Dana. In fact, the only essential difference between the two would seem to consist in a shghtly different structure of the gnathopoda, and hence I thought it right, in the Ist part of my «Oversigt af Norges Crustaceer>, to refer Boeck’s species to the said genus. Meanwhile Dr. Bovalius has recently maintained

the distinctness of Boeck’s genus, though referring the genus Lycea to the

17

same family, and as that author has made the Hyperids his special study, I do not feel at present entitled to dissent from his opinion on this point. In the restricted sense in which the genus is taken by Bovallius, it only contains a single species, for the 7. Nordenskjildi is quite certainly not

specifically distinct.

8. Tryphena Malmi, Boeck. (Ge 7) eTryphana Mali, Boeck, Crust. Amphip. borealia et arctica, p. 9. Syn: JT. Nordenskjoldi, Bovall. = @. » YT. Boeck, Stebbing = ©.

Cephalon about half the length of the mesosome, front in female obtusely rounded, in male angularly produced; ocular pigment rounded oval in male somewhat narrowed dorsally. Mesosome not very tumid, nearly as long as the metasome. First pair of antenne with the 2nd joint of the flagellum in female linear compressed and about the length of the peduncle and Ist joint of the flagellum combined, obliquely truncated at the extremity and bearing 4 sensory appendages; in male much narrower and ciliated on the posterior edge, the spiniform process about as long as the terminal joint, the latter in both sexes scarcely longer than the sensory appendages. Anterior enathopoda with the basal joint about as long as the remaimder part of the leg, propodal joint compressed oval, bearing a short spine on either edge, and produced at the tip, beneath the dactylus. to a short tooth-hke process. Posterior gnathopoda more slender than the anterior ones, outer part very hairy, propodal joint narrow and as long as the dactylus. All the pereio- poda, saving the last pair, having the propodal joint produced at the tip beneath the dactylus to a short tooth-like process; 3rd pair about as long as the mesosome. Basal joint of the 2 posterior pairs of pereiopoda con- siderably more expanded in male than in female. Urosome about as long as the last segment of the metasome, rami of the uropoda subequal. Telson in male somewhat larger than in female, slightly exceeding the basal part of the last pair of uropoda. Colour more or less reddish, speckled with small purplish pigmentary spots. Length of adult female 5 mm, of male 6 mm,

Remarks. The habitus-figure of the female given by Boeck in his work on the Scandinavian Amphipoda is very bad and misshaped, and this may have been the cause why Dr. Bovallius could not recognise the specimen examined by him as the male of T. Malm. True, the sexual differences in this form are rather striking, not only as regards the structure of the antenna, but also in several other points; but on a closer comparative examination ot

both sexes, their specitic identity cannot be misunderstood. The form described 3

18

by the Rey. Stebbing from the Challenger Expedition as 7. Boecki does not seem to differ in any essential manner from male specimens of the present species.

Occurrence. | have tound this interesting form in three different localities on the west coast of Norway, viz., at Folgero and Sunde in Sondhordland, and in the Foldentjord at Apelver. In all 3 places it was procured by the dredge from comparatively great depths, 80—200 fms. Boeck collected his specimens likewise at a considerable depth in the outer part of the Hardangertjord, at Lyngholmen.

Distribution. Off the Fero Islands at Lat. 65° N. (Bovallius); North Atlantic at Lat. 18° 8’ N. (Stebbing).

Fam. 3. Scinidz.

Cephalon small, not tumeficated. Eyes very minute. Superior antenne rather large, straight, styliform, divergent, similar in the two sexes; inferior antenne in female quite rudimentary, in male very slender and angularly bent. Mandibles without palps. Maxille well developed. Maxillipeds with lanceolate terminal lobes. Gnathopoda simple, not subchelate. Pereiopoda very slender, the 3 posterior pairs rather unequal, with narrow basal joints, last pair the smallest. Metasome in female not very powerful, epimeral -plates small. Urosome depressed. Uropoda imperfectly developed, more or less sword-shaped. Telson very minute.