I9I5-] 



Fauiui of the Chilka Lake : Crustacea Decapoda. 



291 



the first legs have attained. In the smallest males (five specimens) one of the first 

 legs, either right or left, is identical in structure with that of the female, while the 

 other is greatly enlarged, the fingers of the chela being curved and not provided 

 with teeth (text-fig. 316). In other males (two specimens) both legs of the first pair 

 are equally enlarged, each being closely similar to the large limb borne by the preced- 

 ing form (text-fig. 31c). In others again (two specimens) both legs are enlarged, 

 but asj'mmetrical ; one limb, except for the greater number of spines on the merus, 

 is similar to that in the preceding group, while the other is a little larger and, apart 

 from more trifling dift'erences in forms, is provided with a huge rounded tooth on 

 the fixed finger (text-fig. 3i(/). 



The characters of the nine males may be tabulated thus : — 



In all these specimens the appendix masculina on the second pleopods is well 

 developed ; there is thus no doubt regarding their sex. Also, it is in my opinion im- 

 possible that the small limb found in Form I is the result of regeneration. In almost 

 all cases it is easy to distinguish a limb that has been broken off and subsequently 

 grown again and it is, I think, inconceivable that in each of the five individuals of 

 this form it should be equally and perfectly re-developed. 



The case therefore is one of trimorphism, at any rate ni a somewhat loose appli- 

 cation of that term ; Init the specimens are so few in number that I have found it 



' The measurement is taken from the posterior mid-dorsal edge of the carapace to the tip of the 



ej'e. 



