352 A. Alcock — Carcinological Fauna of India: [No. 3, 



common^ captured than, the females, is sufficient justification for the 

 common practice of using the larger cheliped of the male for the dis- 

 crimination of the species. It must, however, be remembered that — at 

 least in all tbe Indian species — this organ changes greatly with advanc- 

 ing age. 



I must also confess here that the synonomy of species has defied 

 me. 



Key to the Indian species of Gelasimus. 



I. The breadth of the front, measured exactly between the 

 bases of the eyestalks, is between a fifth and a sixth the 

 greatest breadth of the carapace : — 



1. Two oblique granular ridges on the inner surface 

 of the palm of the large cheliped of the male, one 

 continuous with the dentary edge of the immobile 

 finger, the other running to the lower edge of the 

 same finger : — 



i. Carapace subquadrilateral, the true lateral 

 borders being moderately convergent posteriorly : 

 an enlarged tooth near the tip of the immobile 

 finger of the large cheliped of the male gives the 

 tip of this finger a notched- truncate appearance G. annnlipes. 



ii. Carapace subquadrilateral, the true lateral 

 borders nearly parallel : the tip of the immobile 

 finger of the large cheliped of the male is oblique- 

 truncate but not notched G. lacteus. 



iii. Carapace distinctly hexagonal, owing to the 

 great obliquity of the orbits and the strong con- 

 vergence posteriorly of the true lateral borders : 

 tip of the immobile finger of the large cheliped 

 of the male not truncate or notched G. triangularis. 



2, The oblique crest running to the lower edge of the 

 immobile finger of the large cheliped of the male is 

 either absent or is represented by a slight and 



smooth tumescence G. inversus. 



II. The breadth of the front, measured as above, is very 

 much less than a sixth the greatest breadth of the cara- 

 pace : — 



1. No row of granules running inside of and parallel 

 with the lower border of the orbit : — 

 i. The inner border of the arm of the larger cheliped 

 of the male ends in a sharp tooth or spine, in- 

 dependent of the terminal lobe-like constriction 

 of the arm : — 



a. Front, measured as above, about a tenth 

 the greatest breadth of the carapace : in 

 the large cheliped of the male the wrist is 



