670 



wide intervals; 1st free bodj'-segment in both sexes transversely quadrangular 

 in form, with the lateral corners somewhat exserted; last segment obtusely 

 triangular. Cephalosome occupying about Vs of the length of the body, and 

 considerably attenuated in front. Eyes verj' small, placed dorsally at about 

 the anterior third part of the cephalosome. Superior antennae in female 

 twice the length of the cephalosome, in male somewhat longer, joints of the 

 peduncle slightly diminishing in size, flagellum scarcely more than half the 

 length of the last peduncular joint. Inferior antennae scarcely more than half 

 the length of the frontal margin, basal joint small, rounded, penultimate joint 

 the longest. Anterior gnathopoda with all the joints well defined, propodos 

 in female oval in form, with the lower edge forming in the middle a rounded 

 projection defining the palm, that in male somewhat broader, with a triangular 

 projection in the middle of the palmar edge; dactylus in both sexes strongly 

 curved and very acute. Posterior gnathopoda of same structure in the 

 two sexes, though somewhat larger in the male, basal and ischial joints 

 very short and imperfectly defined, meral joint having outside a lamellar, 

 bifurcate projection, carpal joint very small, propodos, on the other hand, 

 large and tumid, oval pyriform in shape, palmar edge with 2 distant tri- 

 angular projections, the anterior of which is somewhat larger in the male, 

 dactylus extremely strong and ciirved, terminating in a verj' acute point. 

 Branchial appendages in female about half the length of the body, in male 

 considerably longer, and having at the base below a small bilobed lamellae 

 (accessory branchia). Pereiopoda very strongly built, with the meral and 

 carpal joints coalesced, forming outside a rounded expansion, inside an acute 

 projection, propodal joint large, oblong oval in form, with the palmar edge 

 smooth, dactylus strongly hooked. Urosome in female quite simple, forming 

 a very small nodiform appendage containing the terminal part of the intestine, 

 and having at the end on each side a rounded lobe; that in male provided 

 at the base beneath with a membranous appendage divided by a narrow 

 iucision into 2 rounded lobes minutety ciliated on the edges. External 

 sexual appendages in male, issuing from the lower face of the last body- 

 segment, of the usual conical form. Colour light brownish violet, somewhat 

 darker in male than in female. Length of adult female 8 mm., of male 

 12 mm. 



BemarJcs. — There cannot be any doubt that Prof. Liitken is right 

 in believing that the form recorded by 0. Fabricius as parasitic on the Green- 

 land sKeporkaks and named Oniscus ceti is this form and not that so named 

 by Linne, which is the Cyamus mysticeti of Liitken. The C. pacificus of the 

 latter author is very nearly allied to the present species, and this is also 

 the case with C. errafiais of Eouss. & Vaux. From the latter the present 



