DESCRIPTION OF SPECIES 347 



first abdominal segment ; the position of the former suture between the two thoracic 

 somites is indicated by a slight groove. In this respect the species agrees with the con- 

 dition seen in the female of S. aspera, n.sp. (in the male the groove is absent), and is 

 intermediate between S. pagenstecheri, Pfeffer, where only the suture between the seventh 

 thoracic and first abdominal segment is obsolete, and 5. boiwieri, Richardson, and the 

 male of S. aspera, where fusion is complete and no groove indicates the position of the 

 former suture. The coxal plates, which are rather short and closely applied together for 

 their whole length, are developed on each of the third to the seventh thoracic somites ; 

 those of the third to the fifth are separated from their respective somites by sutures. 

 A low prominence is present on either side of each somite near its posterior border and 

 just within the point of union with it and its coxal plate : a groove is present on the dorsal 

 surface of each coxal plate, running parallel with, though a little distance within its 

 anterior margin. Long delicate setae fringe the inner lateral margins of both the coxal 

 and pleural plates. The coxal plates of the seventh thoracic somite extend back to a level 

 corresponding with that of the bases of the uropoda, and slightly beyond that reached 

 by the pleural plates of the third abdominal segment. The pleural plates of the second 

 abdominal segment are a little shorter than those of the third. 



The terminal segment is somewhat pentagonal in outline, terminating posteriorly in 

 a blunt point which is slightly uptilted. The base of the pentagon also forms the base of 

 a somewhat raised, triangular area, which bears a low median keel and extends to about 

 the middle of the segment; the posterior quarter is also slightly keeled. Two longi- 

 tudinal ridges, one on either side, lie near the lateral margins of the segment. 



The peduncle of the antennule is four-jointed ; the first two joints are small, the third 

 one and a half times the length of the second, the fourth about a third of the length of the 

 third. Delicate setae are present on the anterior margin of the first joint and along the 

 anterior and posterior margins of the second and third joints. Neither flagellum is com- 

 plete, but one consists of twenty-five joints, the first eight of which do not bear sensory 

 setae. 



The first peduncular joint of the antenna is short ; the second is three times the length 

 of the first and is fringed with delicate setae ; the third is about two-thirds the length of 

 the second with tufts of setae on its posterior margin ; the fourth and fifth are each three 

 times the length of the third, the fifth being narrower than the fourth. The incomplete 

 flagellum consists of fourteen joints. 



The mandibles are of the usual type ; the primary cutting edges of both are strongly 

 chitinized. The maxillula is of the usual type, with a stout outer lobe bearing eight stout 

 spines and an inner more delicate one on its obliquely truncate distal extremity. The 

 inner lobe is two-thirds the length of the outer and is flattened distally to form an oval 

 plate, the outer margin of which is more curved than the inner. The distal ends of both 

 outer and inner articulated lobes of the maxilla are provided with two strong setae which 

 are minutely pectinate on their inner margins ; the fixed lobe has eight large and about 

 twelve smaller setae at its distal end. 



The basipodite of the maxilliped (Fig. 190) is separated from its lamella, which is 



