344 DISCOVERY REPORTS 



St. 149: South Georgia, 200-234 ^i-; i immature specimen. 



St. 157: South Georgia, 970 m.; i $ (b.). 



St. WS 62: South Georgia, 26-83 m.; 2 ?$ (b.), 2 33, 4 immature specimens. 



St. MS 10: East Cumberland Bay, 26 m.; 2 ?? (non-b.), 3 immature specimens. 



St. MS 67: East Cumberland Bay, 38 m.; i immature specimen. 



Beach, Grytviken, South Georgia; i $ (non-b.). 



Diagnostic characters. The largest male in the collection measures 37 mm. in 

 length and 34 mm. in greatest breadth ; it is slightly broader in proportion to its length 

 than the female, the largest of which measures 38 mm. in length and 32 mm. in breadth. 

 The colour of the living animal is given as dark grey above and white beneath, with the 

 gonads often showing through as orange-red masses. 



The body is broadly ovate, with its dorsal surface covered with scattered hairs which 

 are most numerous along the margins of the segments. The head is broadest anteriorly, 

 with a short median rostrum, behind which is a transverse ridge extending laterally to 

 the sides of the cephalosome. Behind this again is another transverse ridge extending 

 between and in a line with the anterior end of the eyes ; it is lower in the middle than at 

 the sides and immediately posterior to it is a deep groove. The portion of the head 

 between the eyes is strongly convex, and divided into three prominences : in these the 

 posterior margins are much more sharply defined than the anterior which gradually 

 merge into the surface of the head. The lateral prominences are oval and larger than the 

 central one, the latter being in the form of a triangle with the apex directed forwards. 

 The eyes are about half the length of the head, rather narrow, reniform in shape, and 

 containing black pigment. 



The lateral portion of the second thoracic somite, which is fused with the head, has 

 a transverse ridge on each side, commencing at a point in line with the middle of the 

 length of the eye, and running transversely and then slightly backwards, fading away 

 into the lateral margins ; a second short ridge, commencing on either side on the anterior 

 transverse ridge, half-way along the course of the latter on the cephalosome, extends 

 backwards and slightly outwards for a short distance. 



The first three free thoracic somites are sub-equal, with their posterior borders 

 slightly raised to form small median spiniform processes which increase in size from 

 before backwards. The sixth and seventh thoracic somites are narrow, together equal to 

 the preceding one ; the posterior border of the seventh is obsolete in the middle line, so 

 that for a short distance the tergum of the seventh somite is fused with that of the first 

 abdominal segment. The third to the seventh thoracic somites have well developed coxal 

 plates, each of which bears a well marked groove which follows the outline of its anterior 

 margin a short distance within it. The coxal plates of the first three free somites are 

 separated from their respective somites by sutures: those of the seventh somite are 

 produced backwards beyond the pleural plates of the abdominal segments to a point 

 just beyond the level of the articulation of the uropods ; they are longer in the male than 

 in the female. 



Each of the three free abdominal segments has a short median dorsal spiniform 

 process ; the pleural plates of the third segment extend backwards to the level of the 



