1910.] FRESHWATER CRUSTACEA FROM THE TRANSVAAL. 153 



appendages agree closely with the genus Cypris and especially 

 with the subgenus Eurycypris ; from this subgenus it differs 

 in certain characters, the most important of which is the presence 

 of a greater number of foliaceous setae on the biting processes of 

 the maxilla. G. puberoides as described by Vavra {loc. cit.) from 

 German South-West Africa, is not unlike this species, chiefly 

 in the character of the flattened shell, the penis and copulatory 

 styles of the maxilla, and in the character of the antenna, which 

 carries five claws. 



Cypris gunningi, sp. n. (PI. X. fig. 13 ; PL XL figs. 14 a, b, 

 15 a-c, 17 ; PL XII. ; PL XIII. figs. 23 a, b ; PL XV. fig. 36.) 



Length 1*30 mm. ; height, greatest "74 mm., at centre "68 mm. 



External appearance : a lateral view of this animal shows it 

 to be considerably longer than deep, the ratio of the length to 

 the depth being as 2 : 1. The whole surface of the bivalve shell 

 is covered with hairs of moderate length ; they are longest on 

 the ventral marginal edge, becoming shorter near and disappearing 

 on the hinge-line ; on the ventral inner margin of the shell, 

 denticulations are present, which become very minute as they 

 approach the dorsal hinge-line ; these denticulations do not 

 project beyond the outer margin of the shell. 



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



The antenna has the terminal segment considerably thinner 

 than in the foregoing species and the number and length of the 

 seta? and hairs differ slightly ; but two important distinctions 

 are found on the second segment : (1) the swimming-hairs 

 project considerably beyond the claws, a characteristic of the 

 subgenus Gypridopsis ; (2) a row of movable (?) denticulations 

 is developed on that part of the distal marginal edge of the 

 second segment which is opposed to the proximal portion of the 

 third joint (PL XL fig. 14&). The exact function of these 

 tooth-like processes is not perhaps at once clear ; but it may 

 be, that being so placed in conjunction with the distal segment 

 they serve the purpose of locking the second and third segments 

 together in a straight line, thus strengthening the whole ap- 

 pendage for swimming. It is to be noticed that when the 

 appendage is flexed at this point, the denticulations are flexed 

 also. When, however, the third joint is flexed back into a 

 straight line with the second, these processes would be brought 

 up into the same straight line and so form a strong support 

 to the two segments or actually lock them together. 



The mandible is stouter than in G. spinosa ; the two stout 

 hairs on the inner part of the gnathobase are much shorter. The 

 palp differs slightly in that the seta? on the terminal segment 

 are not serrated, the stout plumose seta? on the fourth segment 

 are much shorter, and the palp futhermore differs from that of 

 G. spinosa in the number and character of the seta? on the inner 

 margin of the first and second segments. 



