26o J. G. DE Man : Caridina nilotica. [Voi,. 11^ 



the toothing-formulee of the rostrum of lo specimens are indicated, 

 the other ii specimens show the following toothing ^ : — 



20'^ + 1 20- + I + I , • T -J ^^ 



; (young mdivtdual). 



14 ' II ^-^ ^ ' 



21^ 4-1-1-2 



(young individual). 



13 



22'' -f I 22^ + I -1- I 



23^ + I . 24 — ? ^ 24^ -h 2 , 25"" -I- I^ 

 14 ' 15 ' ~~12 ' 15 ' 



(in this specimen the rostrum is abnormal, quite 



straight, longer than the carapace and than the scaphocerites, 



whereas the proximal row of teeth reaches to the end of the an- 



tennular peduncles ; the teeth of the lower edge are wanting). 



27* 4- '^ 



— z — ^. ~ (the first two or three teeth of the lower 



probably 16 or 17 



margin are grown together, the tip is broken off and the proximal 

 row of teeth reaches beyond the scaphocerites). 



In these specimens the usual number of proximal teeth of the 

 upper margin proves therefore to vary from 20 to 24 and two or 

 three are placed on the carapace. In four specimens one observes 

 an isolated tooth between the proximal row and the subapical 

 tooth, in one case even two isolated teeth are observed. 



Of 16 specimens, in which the tip of the rostrum is well preserved 

 13 are armed with a single subapical tooth, in 2 specimens two 

 are observed and in i even four, but the latter specimen is ap- 

 parently abnormal, because the lower margin carries no teeth at 

 all. In the specimens the rostrum of which is not injured, the 

 number of teeth of the lower margin varies from 11 to 20, there 

 being ordinaril^^ 11, 14, 15 or 16 teeth present. The rostrum com- 

 monly extends beyond the scaphocerites, appearing a little longer 

 than the rest of the carapace. The proportion between the length 

 of the unarmed terminal part of the upper edge and that of the 

 proximal row of teeth is very variable ; sometimes, as in the speci- 

 men figured by Roux, the proximal row appears little more than 

 once and a half as long as the unarmed terminal part (Table A, 

 Nos. 5 — 8), in other cases the unarmed part is shorter and in No. 4 

 it measures barely one- third the length of the proximal row. 



Though the carpus of the ist pair of legs appears usually 

 twice or more than twice as long as broad, it presents sometimes a 

 stouter shape, as in No. 5 of the Table ; in such specimens the car- 

 pus has exactly the same shape as in some individuals of the var. 



1 In each formula near the number of proximal teeth a smaller type indicates 

 how many teeth are placed on the carapace. 



