28o DISCOVERY REPORTS 



b. Pleural plates of second and third abdominal segments extending beyond the 

 anterior margin of the terminal segment. 



1. Coxal plates of seventh thoracic somite extending backwards for about two- 

 thirds of the length of the terminal segment (excluding the terminal spine if 

 present). 



a. Median dorsal portion of the cephalosome produced backwards into a spine 

 which extends to the middle of the fourth thoracic somite 



17. S. gerlackei, Monod. 



/3. Median dorsal spine of cephalosome absent; posterior extremity of terminal 

 segment produced to form a long spiniform process, the lateral margins of 

 which are serrated ; eyes devoid of pigment ... 18. S. meridionalis, Hodgson. 



2. Coxal plates of seventh thoracic somite extending as far, or nearly as far, as the 

 posterior extremity of the terminal segment. 



a. Coxal plates of seventh thoracic somite, in the male, extending backwards 

 almost as far as the posterior extremity of the terminal segment; pleural 

 plates of second and third abdominal segments to a short distance beyond 

 the articulation of the uropod; terminal segment longer than broad; body 

 almost circular in outline ... ... ... ... 19. S. comuta, Studer. 



j8. Coxal plates of seventh thoracic somite extending backwards to a point not 

 far beyond the articulation of the uropod and only just beyond the posterior 

 extremities of the pleural plates ; terminal segment broader than long ; body 

 broadly ovate in shape ... ... ... 20. S. tiiIobitoides,Kights. 



3. Coxal plates of seventh thoracic somite long and extending backwards beyond 

 the posterior extremity of the terminal segment. 



a. Eyes absent; coxal plates comparatively short and flat, those of the seventh 

 thoracic produced backwards to a short distance beyond the posterior ex- 

 tremity of the terminal segment ; pleural plates of third abdominal segment 

 slightly longer than those of the second, and reaching to the basal joints of 

 the uropoda ... ... ... ... ... ...21. S. antarctica,'Btddard. 



^. Eyes present but not deeply pigmented; coxal plates long and spiniform, 

 those of the seventh thoracic somite extending for a considerable distance 

 beyond the extremity of the terminal segment; pleural plates of third ab- 

 dominal segment in the male produced backwards as far as extremity of the 

 terminal segment ; those of second to a short distance beyond : eyes whitish 

 yellow in colour ... ... ... ... ... ... 22. S. brom ley ana, Suhm. 



c. Pleural plates of second abdominal segment extending for some distance beyond 

 the posterior extremity of the terminal segment ; those of the third segment short, 

 not reaching beyond the antero-lateral margin of the terminal segment ; eyes large, 



with bluish black pigment ... ... ... ... ... 23. S. neaera,'Qe.dda.rd. 



n. Hindmost suture of seventh thoracic somite obsolete in the mid-dorsal line, so that for a 

 short distance the tergum is fused with the first abdominal segment; the third to the fifth 

 thoracic somites separated from their coxal plates by sutures. 



A. Hindmost suture of sixth thoracic somite complete. 



I. Coxal plates of seventh thoracic somite tiot extending backwards as far as the posterior 



extremities of the pleural plates of the second and third abdominal segments. 



a. Terminal segment almost triangular in shape, with a dorsal median keel, ending 



posteriorly in a blunt prolongation ; thoracic somites each with median tubercle, 



and free somites each with a lateral tubercle on either side, close to the junction of 



the tergum with its coxal plate... ... ... ... ... 24. 5. W2«tt/a, Beddard. 



