DESCRIPTION OF SPECIES 293 



between the anterior ends of the eyes is a second transverse ridge behind which is a deep 

 groove. The portion of the head between the eyes is raised into three oval prominences, 

 the posterior margins of which are more sharply defined than the anterior. The eyes are 

 large, reniform, with black pigment. 



Each of the third to the seventh thoracic somites is produced in the median dorsal line 

 into a short but distinct spiniform process. The coxal plates are well developed and those 

 of the first three free somites are separated by sutures ; those of the seventh thoracic 

 somite are produced backwards and extend about to the level of the basal joint of the 

 uropoda. The pleural plates of the second abdominal segment extend backwards beyond, 

 and those of the third abdominal segment as far as, the coxal plates of the seventh 

 thoracic somite. The terminal segment is furnished with a well-developed spine in the 

 anterior median line, followed by a median dorsal keel which extends to the extremity. 

 On each side of the median keel there are two lateral oblique ones, terminating in small 

 spines some distance from the lateral margins, which are slightly turned downwards. 



Remarks. The only specimens of this species previously recorded are two males, the 

 type specimen described by Tattersall (1921) and a second one identified by Monod 

 (1926). The present collection contains nineteen specimens, of which nine are adult 

 females and four adult males; all these are smaller than the type specimen, which 

 measures 17 mm. in length and 14-5 mm. in breadth. The largest male in this collection 

 is only 12 mm. long and 10 mm. broad, and the largest female is 1 1 mm. long and 8 mm. 

 broad. 



The specimens agree with the description given for the type, but there appears to be 

 a sexual diff'erence in the number of joints present in the flagellum of the antennule; in 

 the males the number of joints is twenty-eight, compared with thirty-five in the type, 

 whilst in the females the number of joints is only sixteen. A similar sexual diff'erence 

 also occurs in S. kempi, n.sp., and S. aspera, n.sp. 



The form of the cutting edges of the mandibles is shown in Fig. 4 g. The maxillula 

 is of the usual type: the outer lobe bears ten stout curved spines, nine of which are 

 toothed, whilst the tenth innermost one is more dehcate and pectinate; the inner lobe 

 is about two-thirds the length of the outer, and is somewhat expanded for a short dis- 

 tance behind its distal extremity ; the latter bears a single short seta. 



The maxilla bears two spines on its outer, three on its inner, and nine on its fixed 

 lobe; these spines each possess a double row of short pectinations. The maxilliped 

 (Fig. 2 d, e) belongs to the type in which the basipodite is separated from its lamella by 

 a suture ; the lamella is almost square with the angles of its distal extremity rounded. 

 The sexual difference in the form of the coxal joint may be seen from the figures. 



The thoracic appendages have been described and figured by Tattersall (1921, p. 229, 

 pi. vii, figs. 2-5). The protopodite of each of the first three pleopods is triangular in 

 shape, and the produced angle bears three long plumose setae on the first and two on 

 each of the second and third pleopods. The suture of the exopod of the fourth pleopod 

 is almost transverse and the endopod is rounded and undivided. The exopod of the 

 fifth pleopod is also partially divided by a transverse suture which extends from its 



