TANAIDACEA AND ISOPODA— TATTERSALL. 229 



Abdomen (pi. VII, fig. 1) with three free somites and a large terminal one, each 

 of the free somites with a short median dorsal spiniform process in continuation of 

 those of the thorax ; pleural plates of the second somite well produced backwards and 

 extending posteriorly beyond the coxal plates of the seventh thoracic somite ; pleural 

 plates of the third somite shorter than those of the second, and reaching the same level 

 as the coxal plates of the seventh thoracic somite ; terminal segment with a well- 

 developed spine in the anterior median line, followed l^y a median dorsal keel which 

 extends to the extremity ; on each side of the median keel there are two lateral oblique 

 keels, terminating in small spines some way from the lateral margins, which are slightly 

 turned down and infolded. 



First and second antennae (pi. VII, fig. 1) rather long, reaching backwards almost 

 to the posterior margin of the third free segment of the mesosome ; peduncle of the 

 first antenna four-jointed, first two joints small, third joint the longest, three times as 

 long as the fourth, flagellum of thirty-five joints ; peduncle of the second antenna 

 longer than that of the first by the entire length of the fifth joint, fourth and fifth 

 joints long and narrow and equal to each other, fiagellum of about seventeen joints, 

 shorter than the last peduncular joint. 



The second, third and fourth thoracic appendages are shown in the figures 

 (pi. VII, figs. 2-5). The second is stoutly built, with the propodus greatly expanded, 

 having its outer distal corner somewhat pointed, and its inner margin armed with a 

 row of about forty -five broad triangular tooth-like processes alternating with peculiar 

 siout spines. The distal edge of the carpus is crenulate and bears two stout spines. 

 The third thoracic appendage is much smaller than the second, with the propodus 

 modified and bearing on its inner border several short stout spines and larger and 

 more slender setae. Each of the sternal plates of the first three abdominal segments 

 has the median posterior border produced into a spine, increasing in length from the 

 first to the third. 



The appendix masculina on the second pleopod of the male reaches about 

 two-thirds of the way towards the apex of the metasome. 



Uropods not extending beyond the metasome ; endopod and exopod narrowly oval 

 in shape, the exopod scarcely more than half the length of the endopod, margins of both 

 finely serrated and sparsely setose. 



This species appears to be most nearly related to S. septemcarinata, Miers, which 

 has been recently redescribed and figured by CoUinge (1918). I have compared the 

 single type specimen with examples of Miers' species in the present collection and have 

 noted the following points of difference. 



(1) S. glacialis is more fiattened, less compact and more transparent than 

 S. septemcarinata. It should be remarked, however, that the " Terra Nova " specimen 

 has every appearance of having been frozen before preservation, and this may account 

 for its translucent appearance. 



(2) The eyes are larger in S. glaciaiis than in S. septemcarinata. 



