Art. XVIII.—Notes on some New Zealand Amphipoda and Isopoda.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 24, 1891, Page 258

Art. XVIII.—Notes on some New Zealand Amphipoda and Isopoda. By Chas. Chilton, M.A., B.Sc. [Read before the Otago Institute, 10th November, 1891.] During the six years that have elapsed since the publication of a critical list of the New Zealand Amphipoda and Isopoda by Mr. G. M. Thomson and myself,* Trans. N.Z. Inst., vol. xviii., p. 141. much new material has been collected of which no account has yet been published, while the publication of the reports on the “Challenger” Isopoda and Amphipoda, by Beddard and Stebbing respectively, has shown that there are many things that need alteration in the nomenclature of the species already known, and many points concerning them that require more fully working out. To do this properly it would be necessary to begin at the beginning of the list, and to take the species one by one and work each out fully. This, however, would be a work of very considerable magnitude, and would require the continuous attention of the worker for a long time. In the present paper I shall content myself with giving a number of miscellaneous additions to our knowledge on the subject. I describe some new forms, record others already known elsewhere, but new to New Zealand, and draw attention to a few of the changes and additions made in the “Challenger” reports. For material, besides what I have collected myself, I am indebted to Mr. R. M. Laing, of the Boy's High School, Christ-church; to Mr. H. Suter, of Christchurch; and particularly to Mr. G. M. Thomson, Science Master of the Dunedin High Schools, who, feeling unable at the present time, through pressure of other matters, to work at the subject himself, has very kindly handed over to me all the undescribed Amphipoda and Isopoda in his collection, together with many of his own notes and drawings. Among the specimens that I have thus received are many collected by Mr. J. F. Erecson, of Waipa-papa Point, and by Mr. F. S. Sandager, of Mokohinou, both of whom have in this way rendered valuable assistance. Only a small part of the material thus placed at my disposal has been used in the preparation of this paper; I hope to be able to make use of the remainder on some future occasion. In the case of species previously described, I have endeavoured as far as possible to give the reference to our Critical List,* and to any papers published since, but I have

not repeated the references already given in the Critical List. In the case of some species I have given only short diagnoses, hoping to supplement these at some future time with fuller descriptions and figures. In other cases I have mentioned species merely to state what questions require solution. Amphipoda. Talorchestia tumida, G. M. Thomson. Talorchestia tumida, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 145; Stebbing, Trans. Zoological Society (London), vol. xii., p. 202, pl. xxxix.; Thomson, Trans. N.Z. Inst., vol. xxi., p. 260, pl. xiii., figs. 4–8. This species was first briefly described by Mr. Thomson in the New Zealand Journal of Science, vol. ii., p. 577. This description was reproduced in the Proceedings of the Zoological Society for the 19th January, 1886 (p. 4), by Mr. Stebbing, who afterwards fully described and figured the male in the Transactions of the Zoological Society, and Mr. Thomson supplemented this by a description of the female in the Transactions of the New Zealand Institute, vol. xxi., p. 260. The species was originally taken at Purakanui, near Dunedin. I afterwards took it on the Ninety-mile Beach, a few miles north of Timaru; and in Mr. Thomson's collection there is one specimen from Waipapapa Point, collected by Mr. J. F. Erecson. The form of the second gnathopod of the male varies very considerably, apparently according to the growth of the animal, and its development needs working out in this as in many other species of the Orchestidæ. Stenothoe adhærens, Stebbing. Stenothoe adhærens, Stebbing, “Report on the ‘C hallenger’ Amphipoda,” p. 748, pl. xxxix. I have for some years had specimens from Lyttelton Harbour that I now refer without much doubt to this species, which is described by Stebbing from two female specimens taken off Cape Agulhas, South Africa. My female specimens agree very closely with his description; the males, which he had not seen, differ in having the peduncles of the antennæ longer, and especially in the second gnathopoda, which have the propodos very large—about as large as all the rest of the limb; the anterior edge is convex; the posterior edge is straight, and produced distally into a sharp tooth, at the base of which is a small projection on the inferior margin. The dactylos is fully as long as the propodos, and has a slight enlargement on the inner margin, at some distance from the base; its inner margin, and the whole of the posterior margin of the propodos,

against which it impinges, are fringed with numerous short stiff setæ. I had previously thought that this species might perhaps be identical with Montagua marina, Spence Bate, and it certainly appears to resemble that species pretty closely, but whether it is identical or not I cannot venture to say until I have an opportunity of comparing specimens of both species. It may perhaps be the same as Montagua longicornis, Has-well,* Catalogue Australian Crustacea, p. 226. but the description of that species is too brief to enable one to decide. I have lately taken this species at Port Chalmers also. Seba saundersii, Stebbing. 1875. Seba saundersii, Stebbing, Ann. and Mag. Nat. Hist., ser. 4, vol. xv., p. 2, pl. xv., figs. 2, 2a-2c. 1884. Teraticum typicum, Chilton, Trans. N.Z. Inst., vol. xvi., p. 257, pl. xviii., figs. 1, 1a-1f. 1885. Seba typica, Chilton, N.Z. Journal of Science, vol. ii., p. 320. 1886.Seba typica, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 148. 1888. Seba saundersii, Stebbing, “Report on the ‘C hallenger’ Amphipoda,” p. 783, pl. xlix. In the full description given of this species by Mr. Stebbing in the “Challenger” Report he unites my Teraticum typicum with his Seba saundersii, saying that he thinks it must be identical with it. I originally had three specimens of my species, and I still have two of them (now mounted in Canada balsam), and, after having carefully compared them with Stebbing's full description and figures, I am quite convinced that he is right in making Teraticum typicum a synonym. The only point in which they differ is the one referred to by Stebbing—viz., the length of the first joint of the upper antenna. In both my specimens this is only as long as the second, while in his specimen, described in 1875, the second joint is “a little the longer,” and in the “Challenger” specimen “decidedly longer.” His “Challenger” specimen is a female; and so, probably, therefore, was my third specimen, which resembled it in the shape of the first gnathopoda. This specimen was sacrificed for dissection in drawing up my original description. My two remaining specimens differ very considerably in the form of the first gnathopoda, and are probably males.† For description see Trans. N.Z. Inst., vol. xvi., p. 257. The “Challenger” specimen was taken off Patagonia, and Mr. Stebbing's original specimen either from South Africa or

from Western Australia, and mine from Lyttelton, so that the species, though so small, evidently has a wide range. Elasmopus subcarinatus, G. M. Thomson. Mœra subcarinata, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 146. Elasmopus subcarinatus, Stebbing, “Report on the ‘C hallenger’ Amphipoda,” p. 1O19, pl. xcviii. This species is very fully described by Mr. Stebbing, and is by him placed in the genus Elasumopus, Costa, which comes close to Mœra. By the “Challenger” Expedition the species was taken at the following stations:— “Station 161, off Melbourne, 1st April, 1874; depth, 33 fathoms; bottom, sand. Two specimens. “A specimen of this species was labelled as having been taken, ‘3rd June, 1874, off Port Jackson, 30 to 35 fathoms.’ “Station 168, off New Zealand, 8th July, 1874; lat. 40° 28′ S., long. 177° 43′ E.; depth, 1,100 fathoms; bottom, blue mud; bottom temperature, 37.2°. One specimen. In New Zealand this species is pretty common among seaweed, &c., at about low-water mark. I have taken it at Lyttelton and at Port Chalmers, and also on seaweed washed up on the Timaru beach. Mr. Thomson has taken it at Stewart Island; and Mr. Haswell records it from “Port Jackson (very common at low water among Algæ, &c.), Botany Bay; Port Stephens.” Vibilia propinqua (?), Stebbing. (?)Vibilia propinqua, Stebbing, “Report on the ‘C hallenger’ Amphipoda,” p. 1279, pl. cxlvii. I have a few specimens of a Vibilia taken in Port Chalmers that I refer to this species with some doubt. The genus has not been previously recorded from New Zealand, though it is very widely distributed. It contains a large number of species, many of them very much alike, and I have found considerable difficulty in endeavouring to identify my specimens. On the whole I prefer to put it down to V. propinqua, the species which Mr. Stebbing describes in the greatest detail in his “Challenger” report. The only point in which it differs materially from this species is in the telson, which is not “pear-shaped,” but almost circular, being just about as broad as long; the broadest part, however, is a little nearer the base than the end,'so that the telson is slightly oval. In the telson my specimens more nearly resemble V. milnei, Stebbing; but the details of that species, as drawn by Stebbing, differ considerably.

They are, however, he says, perhaps taken from a young specimen. V. viator, Stebbing, again, has the telson more like that of my specimens than V. propinqua has, and seems to be intermediate in this respect between the two, having the telson somewhat triangular, with the corners well rounded, instead of “pear-shaped” or “circular.” Of V. viator Stebbing says, “The uropods and telson are in very close agreement with those of V. propinqua,” though his figures do not agree quite so closely. It is very easy, however, to make a considerable difference in figures drawn even as accurately as possible, when taken from different specimens of the same species; and Mr. Stebbing's remarks lead me to think that possibly the telson of V. propinqua is not always so distinctly pear-shaped as shown in his figure, but may sometimes approach somewhat to a more circular form. Certainly the several species mentioned are very closely allied, and probably should be looked upon as local varieties of a widely-dispersed species rather than as distinct species. Vibilia gracilis, Bovallius, resembles V. milnei in having a round telson; but I have not been able to get a description of this species. I give the following description of the telson and uropoda of my specimens:— Telson as broad as long, nearly circular but broadest towards the base, margins quite entire. First uropoda with the peduncle reaching as far as the end of the peduncle of the second uropoda, its outer margin serrated towards the end, rami subequal, outer one with outer margin rather coarsely serrate, inner margin with two large serrations near the end and the rest minutely serrate, inner ramus with both margins serrate towards the end: second uropoda with rami subequal, shorter than those of first uropoda, outer ramus with its outer margin somewhat coarsely serrate, inner margin minutely serrate; inner ramus with outer margin minutely serrate, inner margin entire except towards the end, where it is minutely serrate: extremities of the rami of first and second uropoda acute: third uropoda with the peduncles broad but narrowed at the base, margins entire, rami about as long as those of second uropoda but broader; outer ramus with outer margin convex, entire, inner margin minutely serrate, one or two minute setæ placed at the rather blunt extremity; inner ramus with its outer margin minutely serrate throughout, inner margin with minute serrations, which incrcease towards the extremity, which is acute, and tipped with a minute seta. The fifth and sixth segments of the pleon appear completely coalesced. Colour.—The Vibilia is reddish in colour, the colour being

found chiefly on the body, and being somewhat irregularly scattered. The eye, which is fairly large, is of a darker and more brilliant red. Hab. Taken in Otago Harbour in company with a Salpa that is common on Ocean Beach and in Otago Harbour usually about March. The Vibilia appears to be associated with the Salpa, perhaps as a commensal, for I have never taken it except in company with the Salpa, and one specimen was taken actually in the branchial cavity of the Salpa. Euthemisto thomsoni, Stebbing. Euthemisto thomsoni, Stebbing, “Report on the ‘C hallenger’ Amphipoda,” p. 1414, pl. clxxiv., clxxv. Themisto antarctica, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 151 (non Dana). This species differs, according to Mr. Stebbing, from Themisto antarctica, Dana, as in that species the back is not dentate,. and the third peræpods are very strikingly longer than the fourth and fifth. Mr. Stebbing has therefore renamed it in compliment to Mr. Thomson. The name of the genus was altered by Bovallius in 1887, as the name Themisto was preoccupied. The species appears widely distributed in the southern seas. By the “Challenger” it was taken “between Marion Island and the Crozets,” “off Crozet Islands,” “in the Southern Ocean,” and “south of Australia.” It is sometimes washed up on Ocean Beach, Dunedin, in great numbers. Mr. Stebbing draws attention to some specimens which vary in some slight respects from the more typical specimens. Isopoda. Idotea lacustris, G. M. Thomson. [For synonymy see Trans. N.Z. Inst., vol. xxii., p. 194.] This species was originally taken from the Tomahawk Lagoon, near Dunedin, in fresh water. Specimens that apparently belong to the same species are in the British Museum collections from Port Henry, Straits of Magellan (Dr. R. P. Coppinger). In January, 1891, Messrs. William Cron and D. Strachan brought me, from the Mihiwaka Creek, specimens that appeared to belong to the same species; and I have since taken it there myself in considerable abundance. The specimens were found near the place where the creek flows under the railway line at the mouth of the Deborah Bay Tunnel, near Port Chalmers. This place is perhaps about 200ft. above the sea; but the animal was also found both above and below this spot, and probably inhabits the whole creek, which flows down from Mount Mihiwaka, a mountain nearly 2,000ft. high.

I have since taken it also in a stream at Waitaki, some miles from Mihiwaka, and on the opposite side of Blueskin Bay. On examination these specimens proved to differ from the Tomahawk specimens in several small points. I have already briefly mentioned these in the New Zealand Journal of Science, vol. i. (new issue), p. 131 (1891), but it will be as well to give them here in greater detail. 1. In the front margin of the head there is a small depression in the centre, which makes the middle portion appear more deeply emarginate than the rest of the front margin. 2. The eyes are much smaller, being only about half as large. 3. The inner antennæ (antennules) are rather more slender, and are longer, usually reaching to the end of the third joint of the peduncle of the outer antennæ; while in the Tomahawk specimens they do not usually reach beyond the end of the second joint. 4. The outer antennæ are more slender both in the peduncle and in the flagellum. 5. There is only one pair of sutures on the terminal segment of the abdomen. In the Tomahawk specimens there are two; the anterior one, though quite distinct, is small, and extends only a short distance towards the median line. The second one is more distinct, and extends nearly to the centre. It is the anterior pair of sutures that is wanting in the Mihiwaka specimens, while the second one, too, is somewhat less distinct. In this respect the Mihiwaka specimens agree with the figure given by Miers of a Magellan specimen, in which only one pair of sutures is shown. 6. The extremity of the abdomen is slightly more narrowed, not quite so broadly rounded as in the Tomahawk specimens. 7. The colour is usually much lighter, being a light-brown with darker spots and markings. The specimens from Tomahawk Lagoon are usually of a uniform dark greenish-grey. It is also worthy of note that in none of the Mihiwaka specimens have I found the characteristic setæ found on the outer antennæ and on the second pair of legs of the males of the Tomahawk specimens.* See Trans. N.Z. Inst., vol. xxii., p. 195. The differences between the two forms, though not great in amount, are thus seen to be somewhat numerous, and I have found them to be constant by the examination of a considerable number of specimens from each locality. Instead of erecting the Mihiwaka form into a distinct species, it will, I think, in this case be more convenient and less misleading if it is given the same name but is considered as a separate

variety. The Tomahawk form might be denoted Idotea lacustris, var. a, and the other I. lacustris, var. β. Cleantis tubicola, G. M. Thomson. Cleantis tubicola, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 156; Thomson, Trans. N.Z. Inst., vol. xxi., p. 264, pl. xiv., figs. 5–8; Chilton, Trans. N.Z. Inst., vol. xxii., p. 203. This species has hitherto been known from a single specimen only, collected at Auckland by Mr. R. Gillies. In Mr. Thomson's collection I find one (damaged) specimen from Waipapapa Point, collected by Mr. J. F. Erecson, and three specimens taken by Mr. Thomson himself “on the beach, Judge's Bay, Auckland.” All are considerably larger than the type specimen, and are about 16mm. in length. Of the three specimens from Judge's Bay, Auckland, one is a male, and the other two females. I have compared these specimens with the description as given in my “Revision of the N.Z. Idoteidæ,”* Trans. N.Z. Inst., vol. xxii., p. 203. and make the following notes:— The front margin of the head is very slightly concave, and the head is only slightly produced backwards into the first segment of the thorax. The fourth and fifth joints of the antennæ are subequal, and rather longer than the preceding joints; the flagellum consists of a single joint, about as long as the last joint of the peduncle, and bears a thick tuft of short setæ on the inner side. The legs of the male are not quite so short as in the type, which is probably a young specimen, but the fourth pair is short as described. The epimera of the second to fourth segments are small, oblong; the others produced acutely backwards. Colour dark-brown, nearly black, much darker than the type. In the female bearing young in the brood-pouch the body is of the same width throughout, and not expanded as in some species of Idotea, but the fourth and fifth pairs of legs are considerably shorter than the sixth and seventh, and somewhat shorter than in the male. The third specimen is a female, with small brood-plates developed on the fourth and fifth segments. The legs are rather short, as in the other female. The type specimen was found in a tube, which appears to be part of the hollow stem of some plant; but these specimens were taken “on the beach,” and no mention is made of any tube; hence the occurrence of the type specimen in the tube was no doubt accidental, though it is perhaps worthy of note as showing how a habit of dwelling in tubes may be commenced.

Iais pubescens, Dana. 1852. Jæra pubescens, Dana, United States Exploring Expedition, Crustacea, vol. ii., p. 744, pl. xlix., figs. 9a-9d. 1883. Jæra novæ-zealandiæ, Chilton, Trans. N.Z. Inst., vol. xv., p. 189. 1886. Jæra neo-zelanica, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 157. 1886. Iais pubescens, Bovallius, “Notes on the Family Asellidæ,” Bihang till K. Svenska Vet.-Akad. Handlingar, band xi., No. 15, p. 50. 1886. Jæra pubescens, Beddard, “Report on the ‘C hallenger’ Isopoda,” part ii., p. 19, pl. ii., figs. 6–10. 1888. Iais neo-zelanica, Thomson, Trans. N.Z. Inst., vol. xxi., p. 265. I have little doubt that my Jæra novæ-zealandiæ is the same as Jæra pubescens, Dana. When I described it I was not acquainted with Dana's species, but subsequently I saw his figure in the copy of his atlas in the library of the Canterbury Museum; and, as there is no copy of the text in that library, Mr. Alexander Morton, of the Tasmanian Museum, Hobart, was good enough to copy out the description for me from the copy in the library of the Royal Society of Tasmania. From these I judged that the two species would most likely have to be united, and this conclusion was confirmed by the fuller description given by Beddard in the “Report of the ‘C hallenger’ Isopoda.” My specimens agree very closely with Beddard's description, but his figure does not appear altogether satisfactory, and in some points does not correspond with his description. Thus, there appears no warrant for the notches shown on the sides of the head, and apparently also on the bases of the antennæ; the first segment of the pereion is not shown longer than the succeeding, as it is described, and as it really is; and the lateral margins of the segments do not show the division into lobes mentioned, nor the arrangement of setæ thereon as described. Dana's specimens of Jæra pubescens were taken in a semiparasitic condition on Sphæroma lanceolatum at Patagonia; and specimens, which Beddard identifies with Dana's species, were obtained during the “Challenger” Expedition at Kerguelen Island in a similar condition on a Sphæromid, which Beddard identifies as Sphæroma gigas, a species which is, he says, hardly distinguishable from Sphæroma lanccolatum. My original specimen of Jæra novæ-zealandiæ was not taken directly from a Sphæromid, but was found in a bottle with other Crustacea from Lyttelton Harbour, though I do not know the exact circumstances of its capture. Since then I have taken specimens of the same species at Akaroa, creeping

freely on seaweed. However, in July, 1889, I found two small specimens, which evidently belong to the same species, on a large Sphæroma (probably S. obtusa, Dana) in Port Chalmers. They were on the under-surface of the body, between the ventral surface and the bases of the legs, not attached to the body, but creeping about freely. They are small, and evidently immature. The discovery of these specimens living in a semi-parasitic condition, in the same way as Dana's specimens, tends to confirm the conclusion previously arrived at as to the identity of the two species. Mr. Thomson's specimens were taken at Auckland between tide-marks; but whether they were on Sphæromids or not is not now known. From Akaroa I have altogether six specimens: two of them are mature females, each bearing six eggs in the broodpouch. Even these mature specimens are small, only about 2.5mm. long. The others are smaller, two of them very nearly as small as those taken from the Sphæroma in Port Chalmers—i.e., only 1.25mm. long. They all agree closely both with my type specimen and with Beddard's description of Jæra pubescens, Dana. This species is therefore now known from Patagonia, Kerguelen Island, and New Zealand, and it appears that it may be semi-parasitic (commensal) on Sphæromids, or may live freely on seaweed, &c. Perhaps it is semi-parasitic only when young. I leave the species in the new genus Iais, established by Bovallius for those species with tri-unguiculate dactyla to the pereiopoda. Jæropsis neo-zelanica, sp. nov. Body narrow-oblong, breadth about one-fourth the length. Head rectangular, about as broad as long, narrowing at its junction with the pereion, produced slightly into a rostrum between the bases of the antennæ; end of rostrum emarginate, and with a rounded lobe fitting into the emargination. Eyes somewhat large. Segments of the pereion subequal, widely separated laterally; lateral margins rounded and entire. Pleon broadly-ovate, rounded at the end; lateral margins serrated and bearing a few setæ. Antennæ very short, not so long as the head; inner one composed of five joints, the first very large, longer than the two succeeding, the others diminishing in size distally, the last bearing a small tuft of setæ; outer antennæ having the third joint much the largest, with the integument expanded laterally above, fourth joint narrow at the base expanding distally, bent outwards almost at right angles to the third, fifth somewhat longer than the fourth, followed by a short flagellum consisting of five or six

joints which rapidly diminish in size; a few short setæ are present on the fifth joint of the peduncle and on the various joints of the flagellum. Uropoda inserted in lateral emarginations, at the end of the pleon; peduncle consisting of a somewhat large joint slightly more than filling the emargination, the rami represented by small lobes each bearing a few rather long setæ. Opercular plate under the pleon consisting of a single piece, ovate in form, bearing indistinct marks of a longitudinal suture along the middle and a transverse one towards the distal end. Length about 2.5mm. Colour whitish, with scanty marblings of greyish-brown. Hab. Akaroa: a single specimen on the under-surface of a stone exposed at low tide. Lyttelton: a single imperfect specimen forwarded by Mr. R. M. Laing. This species appears to resemble Jæropsis marionis, Beddard, somewhat closely, but differs in the uropoda, the antennæ, &c. Munna neo-zelanica, Chilton, MS. Male.—Body narrow-elliptical, length about two and a half times the greatest breadth. Head not broader than first segment of pereion, deeply notched on each side for the bases of the antennæ; front margin straight, with rounded upper lip attached; the lateral portion behind the insertion of the antennæ has the anterior angle somewhat acute, the posterior angle rounded and slightly produced and bearing the moderately-sized eyes. First four segments of the pereion subequal in length, gradually increasing in width up to the fourth, which is the widest; next three segments subequal, slightly shorter than the preceding, curving slightly backwards at the sides; all the segments having the lateral margins straight or slightly rounded. Pleon as long as the four preceding segments of the pereion, pear-shaped, narrowing posteriorly, extremity rounded. Antennules with the first two joints stout, others slender, reaching a little beyond the end of the third joint of the antennæ. Antennæ considerably longer than the body. First pair of legs very large and strong and of peculiar shape, the basos small, ischios very thick and strong, hollowed anteriorly to receive the distal end of the limb when bent back; carpus expanding distally, mallet-shaped; propodos small and rounded. Succeeding legs of normal shape, last three pairs longer than the others, about as long as the body. Female with the body of the same shape as in the male, not broader; differs from the male in the first pair of legs, which are short and imperfectly subchelate, carpus broader

than the propodos, having the inner edge armed with six strong spiniform setæ. Length about 3mm. Colour brownish, more or less closely covered with darker dots and stellate markings. Hab. Port Chalmers and Brighton, near Dunedin, between tide-marks. A full description of this species, with numerous figures, has been sent to the Annals and Magazine of Natural History. Pseudæga punctata, G. M. Thomson. Pseudæga punctata, Thomson and Chilton, Trans. N.Z. Inst., vol. xviii., p. 153. This species was originally taken on Ocean Beach. It has since been taken by Mr. Suter at New Brighton, near Christchurch, feeding on decaying specimens of Mactra æquilatera. His specimens agree closely with Mr. Thomson's description. Sphæroma (?) egregia, sp. nov. Body rather convex, smooth. Total length of pereion and pleon slightly greater than twice the greatest width. Head transverse, nearly three times as broad as long; first segment of pereion as long as any two of the succeeding, the others subequal in length. Pleon longer than the five preceding segments of the pereion, triangular, the extremity produced backwards and with the sides rolled in below so as to form a kind of funnel, a round opening being left at the end. Pleon distinctly divided into two segments, the first produced backwards on each side into the terminal segment and bearing a suture on each side. Uropoda with the outer ramus much smaller and shorter than the inner, which extends as far back as the cavity, beneath the pleon, but not to the end of the funnel. Antennæ slender, inner (upper) a little shorter than the outer, which reaches backwards nearly to the end of the first segment of the pereion. Legs subequal, short. Colour whitish, with darker markings (slightly red in dried specimens). Length about 3mm. Hab. Akaroa: two or three specimens only. The character of the pleon in this species is very peculiar, and in this it differs in a marked degree from the normal Sphæromæ, but I forbear increasing the confusion that already exists in that group by the addition of another genus, in the hope that some one will soon undertake a revision of the whole of the Sphæromidæ.