284 



Memoirs of the Indian Museum. 



[Voi,. V, 



Family ALPHEIDAE. 



Five species of Alpheidae occur in the Chilka Lake, but only two of them, 

 Alpheus crassimanus and A. paludicola, inhabit the main area. All of them are able 

 to exist in pure fresh water as well as in water as salt as that of the Bay of Bengal 

 in the vicinity of the lake. The species of Athanas is remarkable for the existence 

 in the males of a well-marked trimorphism. 



Genus OGYRIDES, Stebbing. 



i860. Ogyris, Stimpson, Proc. Acad. Nat. Sei. Philadelphia, XII, p. 36. 



1899. Ogyris, Coutière, Ann. Sei. nat., Zool. (8), IX, p. 332. 



1911. Ogyris, de Man, Decap. ' Siboga ' Exped., II, Alpheidae, p. 135. 



1914. Ogyrides, Stebbing, Ann. S. African Mils., XV, p. 31. 



The name Ogyrides has recently been proposed by Stebbing in substitution for 

 Stimpson's Ogyris, preoccupied by Doubleday (1847) in Lepidoptera. 



The genus is extremely abnormal in type, exhibiting in the feeble dimensions of 

 the first peraeopods a condition which is in all probability primitive, while the attenu- 

 ated eyestalks, the form of the antennular peduncle and antennae, the great length 

 of the exopods of the first two pairs of maxillipedes and the reduced branchial for- 

 mula are indications of extreme specialization. The relationship of Ogyrides. with 

 more typical Alpheidae is traced through Automate, a. genus in which the antennular 

 peduncle and antennal carpocerite are of great length and in which, as in Ogyrides, 

 the eyes are not concealed. 



The branchial formula of the species of Ogyrides found in the Chilka Lake is as 

 follows : — 





VII. 



VIII. 



IX. 



X. 



XL 



XII. 



XIII. 



XIV. 



Podobranchs 



Arthrobranchs 



Pleurobranchs 



ep. 



ep. 



ep. 



1 



1 



1 



I 



I 



The branchiae are fewer in number than in any other genus of Alpheidae ; but, 

 except for the absence of an arthrobranch at the base of the third maxillipede, the 

 formula resembles that found in Cheirothrix and Synalpheus. 1 



The single species of this genus found in the Chilka Lake appears to find its 

 nearest ally in a form recorded from the mouth of the Tocantins River in Brazil. 



Ogyrides striaticauda, sp. nov. 



The rostrum is flat and triangular and slightly curved downward distally ; it 



scarcely reaches beyond the infero-orbital angle of the carapace (text-figs. 28a, b). 



The apex is acute and the margins are furnished with setae. Behind it the carapace 



is keeled in the mid-dorsal line for nearly half its length, the carina bearing a series of 



1 Cf. Coutière, Aim. Sei. nat., Zool. (8), IX, p 276 et seq. (1899). 



