44 DISCOVERY REPORTS 



Sars' figure of tumidus (1895, pi. xviii, fig. 1), the margins strongly serrulate except the 

 outer margin of the outer ramus which is smooth. 



The specimens from St. 170 have the antero-lateral angle of the head more like 

 Schellenberg's fig. 10 a than Walker's; perhaps the blunter angle is characteristic of 

 younger specimens. 



Schellenberg himself remarked on the differences between the 'Gauss' and the 

 'Discovery' (1901-04) specimens. 



Distribution. McMurdo Sound. 



Aristias collinus, n.sp. (Fig. 8 c, d). 



Occurrence: 1. St. 170. South Shetlands. 1 immat. (?) 9 mm. Type. 

 2. St. 175. South Shetlands. 1 juv. 7 mm. 



Description. Distinguished at once from antarcticus by the rounded upper lip, and 

 the much deeper dorsal depression on pleon segment 4, which is followed by a rounded 

 hump or boss (not a carina). Telson with the lobes angularly bevelled off distally as in 

 Schellenberg's fig. 10 b (feebly so in no. 2, but distinctly so in no. 1). 



c. 



Fig. 8. Aristias antarcticus, Wlkr. a. Pleon segments 3-6. b. Profile of epistome and upper lip. 

 Aristias collinus, n.sp. c. Pleon segments 3-6. d. Profile of epistome and upper lip. 



Remarks. I fully expect that, though this species resembles the 'Gauss' specimens 

 from Kerguelen (referred by Schellenberg to antarcticus), the latter will be found to be 

 distinct if the upper lip be closely examined. 



Ambasiopsis, Brnrd. 

 Barnard, 1931, p. 425. 



Agreeing with Metambasia, Steph. 1923, but differing as follows : 1st gnathopod feebly 

 subchelate, outer plate of maxilliped non-spinose, inner ramus of uropod 2 not con- 

 stricted, peraeopods 3-5, especially 5, much shorter and 4th joint more expanded, 3rd 

 joint of antenna 2 not expanded. 



The last character is provisional as the only $ (see uncinata, infra) may not have 

 attained its adult characters. 



Ambasiopsis georgiensis, Brnrd. (Fig. 9). 

 Barnard, 1931, p. 425. 

 Occurrence: St. 159. South Georgia. 3 ovig. ?? 10-11 mm. 



Description. Integument indurated. Head with antero-lateral angle pointed. Eyes 

 not visible. Peraeon dorsally rounded. Side-plate 1 subtriangular, pointed below, the 



