290 



Memoirs of the Indian Museum. 



rvoL. v, 



c* 1 



First pair of peraeopods. 



Species. 







Male. 



Female. 



Group of A. nitescens. 







A. nitescens, Leach 



Asymmetrical, both enlarged 



Asymmetrical, one only a little en- 

 larged. 



A. naifaroensis, Coutière. . 



Unknown. . 



Symmetrical, not greatly enlarged. 



A. aretiformis, Coutière . . 



One enlarged, the other unknown 



One not greatly enlarged, the other 

 unknown. 



A. grimaldi, Coutière 



Symmetrical, enlarged 



Symmetrical, enlarged. 



A. granti, Coutière 



Asymmetrical, both enlarged ? . . 



Asymmetrical, both enlarged ? 



A. parvus, de Man 



Unknown.. 



Symmetrical, not enlarged. 



Group of A. dimorphus. 







A. dimorphus, Ortmann. . 



Symmetrical, enlarged 



Symmetrical, not enlarged. 



A. minikoensis , Coutière. . 



Asymmetrical, both enlarged 



Asymmetrical, one only enlarged. 



A. haswelli, Coutière 



Unknown.. 



One (? both) not enlarged. 



A. orientalis, Pearson 



Unknown. . 



Asymmetrical, one only enlarged. 



A. djiboutensis, Coutière. . 



Asymmetrical, both enlarged 



Asymmetrical, one only enlarged. 



A. sibogae, de Man 



Asymmetrical, both enlarged 



Asymmetrical, both enlarged. 



A. jedanensis, de Man . . 



One enlarged, the other unknown 



Symmetrical, not enlarged. 



A. tenuipes, de Man 



Unknown. . 



Unknown. 



The single species of Athanas found in the Chilka L,ake belongs, apparently, to a 

 form hitherto unknown, but is closely allied to Ortmann's A . dimorphus. It was unf or- 



azu. 



Fig. 31. — Athanas polymorphus , sp. nov. 



a. First peraeopods of female. 



b. do. of male, form I. 



c. First peraeopods of male, form II. 



d. do. of male, form III 



tunately very scarce, and of the twenty-seven specimens obtained only nine are males. 

 These nine males, however, present a most notable diversity of form, a fact which 

 has led me to assign to the species the name Athanas polymorphus. 



As in A. dimorphus the first legs in the female are both slender (text-fig. 31a), 

 with the carpus longer than the chela and are wholly dissimilar in structure from the 

 large limbs of the male. But, apart from this feature, which evidently influenced 

 Ortmann in his choice of a specific name, the males in the new species can be sepa- 

 rated into three clearly defined groups according to the degree of development which 



