1910.] FRESHWATER CRUSTACEA FROM THE TRANSVAAL. 155 



Appendages. — All the appendages are similar to those of 

 C. chrissiensis except the following : — - 



The mandible, which is somewhat slimmer. 



The fifth post-oral appendage : the terminal bristle is as 

 long as the third segment. The median seta of the third 

 segment and terminal seta of the second segment are short as 

 in C. mastigophora. 



The maxillary accessory copulatory structures are longer and 

 thinner than in C. gunningi. The basal joint of one is very 

 thick and stout, but of the other thin and long. 



OYPRIS MASTIGOPHORA, Sp. II. (PI. XI. fig. 18; PI. XIV. 



figs. 31, 32 ; PL XY. fig. 38.) 



Length *52 mm. ; height "25 mm. External appearance : 

 viewed from the side the ratio of the length to the depth is 

 roughly as 2:1. The hind-end tapers considerably ; the fore- 

 part ends bluntly. Fairly long hairs cover the surface and 

 margins of the shell ; denticulations are absent. 



Appendages. — The antennule is typical of the genus Cypris. 



The antenna : the swimming hairs extend beyond the claws. 



The mandible : the disposition and number of seta? and bristles 

 on the palp are different from such as are found in the foregoing 

 species. The terminal joint bears two large stout bristles and 

 one small seta ; the third segment is furnished with one large 

 plumose bristle, and four seta?, three plumose, on the inner 

 margin ; on the external surface one short and three long seta?, 

 and a group of hairs just behind these structures. The third 

 segment of the palp bears on the external margin two long smooth 

 seta?, and on the internal margin five stout pectinose bristles. 

 The second segment is provided on the internal surface with 

 three thick bristles, two of which are pectinose. 



The maxillula : the terminal bristles of the palp are stouter 

 than in C. gunningi. On the third biting process, in addition 

 to the two foliaceous bristles, a number of fine seta? are developed 

 below the extremity. Foliaceous bristles on the other biting 

 processes are absent. 



The maxilla does not differ from C. gunningi. 



The fourth post-oral appendage : the third segment consists 

 of two pieces ; the appendage is practically similar to that of 

 C. gunningi, except for the presence of additional seta? at the 

 terminal end of the fifth segment and in the arrangement of 

 some minute hairs about the second segment. 



The fifth post-oral appendage : the median seta on the third 

 and the end seta on the second segment are much shorter than in 

 0. spi?wsa ; otherwise similar in structure. 



The caudal furca differs from that of any of the other Cyprida? 

 described here in that the rami consist of long thin whip-like 

 processes with one short seta at the base, a character peculiar 

 to the subgenus Cypridopsis. 



Remarks. — This species w r as comparatively rare ; unfortunately 



