LYSIANASSIDAE 



53 



Remarks. A casual glance at the serrate pleon segment 3 might lead one to expect 

 that this form was Tryphosites chevreuxi, but the epistome is distinctive. The serrations 

 on pleon segment 3 and on the 2nd joints of peraeopods 3-5 are less strong than in the 

 latter species, the carina on pleon segment 4 is more prominent, and the telson longer. 



Tryphosa castellata, n.sp. (Fig. 18). 



Occurrence: St. 222. Cape Horn. 2 ovig. $$ 11-5-12 mm. 



Description. Close to analogica, but easily distinguished by the bluntly rounded 

 antero-lateral angle of head, the more narrowly rounded 

 and less prominent epistome, the distally widened 

 1st side-plate, stouter 1st gnathopod, the low rounded 

 carina on pleon segment 4, and the less produced postero- 

 inferior angle of pleon segment 3, with its fewer and 

 squarer denticles. 



Tryphosa onconotus, Stebb. 



Stebbing, 1908 {Ann. S. Afr. Mm., vi), p. 65, pi. xxxv. 

 Schellenberg, 1926, p. 276, fig. 20 (juv.); 1926 b, p. 219. 



Occurrence: St. 91. South Africa. 2^5 mm., 5 $$ 4—5*5 mm. 

 (all immat.). 



Remarks. Schellenberg is quite right in suggesting 

 that the acute point on the postero-inferior angle of pleon 

 segment 3 is characteristic of the young. In half-grown specimens it still remains as a 

 minute blunt and obscure point, but in the adult, as in Stebbing's figure, there is no 

 trace of it. 



The original specimens did not come from "False Bay" as Schellenberg (1926) 

 states, but from off the west coast of the Cape Peninsula. 



The species is evidently a cold-water form ; its occurrence in False Bay does not dis- 

 prove this statement, as cold currents frequently round the Cape of Good Hope and 

 enter False Bay. It is possible that this species migrates in from the outer waters with 

 these currents ; both the present record and the ' Gauss ' specimens were taken in winter 

 (September and July respectively). The surface temperatures in Table Bay and False 

 Bay differ but little at this season (cf. Gilchrist, 1902, Mar. Invest. S. Afr., 1, p. 203, 

 pi. vi). 



Distribution. South Africa, off Table Bay, 448 m.; Simons Bay, littoral; off west 

 slope of Agulhas Bank, 564 m. Also specimens in the South African Museum from off 

 Saldanha Bay, 87 fathoms. 



Fig. 18. Tryphosa castellata, n.sp. 

 a. Pleon segments 3 and 4 with 

 serration further enlarged, b. Anterior 

 margin of head with epistome and 

 upper lip. 



