1908,] Records of the Indian Museum. 259 



between 20 and 24 ; ova 



usually 0'45 or 0*46 mm. 



long, varying between 0*42 



and 0*49 mm. . . var. bengalensis, nov. 



aa. Dactylus of 3rd pair about 



^ the length of the propo- 



dite (number indicating the 



proportion between the 



length of both joints vary- 

 ing between 5"8 and 6-2) ; 



dactylus of 5th pair \ — \ 



of the propodite. Ova 



0*39 — 0*44 mm. long . . var. brachydactyla, nov. 

 II. Number indicating the proportion 

 between length and breadth of 

 the carpus of ist legs usually less 

 than I '8, rarely rising to i'9, but 

 never reaching to 2. 

 /. Number indicating the pro- 

 portion between the length 



of propodite and dactylus 



of 3rd pair larger than 5^ 



of 4th pair, 4. . . var. wyckii (Hicks.), 



//. Number indicating the pro- 

 portion between the length . ' 



of propodite and dactylus 



of 3rd pair usually less than 



4, rarely reaching to 4*2; 



that of 5th pair always less 



than 4. 

 g. ova 0*55 mm. long . . var. minahassa, de M. 



gg. ova 0'33 — 0*39 mm. long. . . var. longirostns,H. M. Edw. 



Whereas in the foregoing key the principal characters are in- 

 dicated by which the varieties may be distinguished, the following 

 part contains my observations on the rostrum and on the thoracic 

 legs. 



I. Caridina nilotica (Roux), typical form. 



TABI.E A. 



(Plate XX, figs. I, la, lb.) 



In the figure of Roux's quoted paper of 1833, the rostrum 

 extends distinctly beyond the antennal scales ; its upper margin 

 carries 13 teeth, two of which are on the carapace, there is no 

 subapical tooth, and the lower margin is armed with 14 teeth. In 

 the 21 specimens from Cairo which lie before me, not one presents 

 such a small number of teeth on the upper margin. On Table A 



