222 Memoirs of the Indian Museum. [Voi,. V, 



those that were younger were compelled to live higher up, close to and among the roots 

 of the grass. A detailed and most interesting account of the habits of this and other 

 species of Gelasimus has lately been published by Pearse L , who finds reason to dissent 

 from some of Alcock's views' 2 as to the use of the large claw of the male as a means 

 of sexual attraction. In this connection it may be mentioned that large claws of the 

 male, in the rather diminutive specimens found in the Chilka Lake, were for the most 

 part white and showed only the faintest trace of the deep pink colour which charac- 

 terises well-grown specimens of the species. There was no indication of the bright 

 blue bands which Nobili 3 noticed in certain specimens from S. India. 



At the period when the specimens were found, the water in the outer channel was 

 as salt as that of the open sea in the vicinity of the lake. In September of the same 

 year, when it was quite fresh, the colony had entirely disappeared, though whether 

 the individuals were killed off by the fresh water or were induced, by reason of it, to 

 migrate to a more favourable spot remains a matter of conjecture. No specimens of 

 the species were found anywhere in the outer channel in September 19 14, though a 

 single example was obtained in the same month of the preceding year on the shore 

 at Satpara ; the example may possibly have been brought there by the fishing boats, 

 but this seems unlikely. 



The evidence available appears, therefore, to point to the fact that the species is 

 unable to withstand the periodical freshwater floods, and to this conclusion the small 

 dimensions of the specimens also lends colour. Certain other species of amphibious 

 Crustacea found in the outer channel (Ocypoda, Dotilla pertinax and Cardiosoma) seem, 

 on the contrary, in no wise affected by the great changes in salinity. 



Subfamily SCOPIMERINAE. 



Genus DOTILLA, Stimpson. 



Dotilla pertinax, sp. nov. 



(Plate XII, fig. 4.) 



The carapace is broader than long in the proportion of 4 to 3 and is strongly areo- 

 lated and grooved; the grooves are always smooth, while the areolae are for the 

 most part either tubercular or clothed with short stiff setae. 



From the front a deep groove runs backwards and bifurcates almost imme- 

 diately; its two branches are continued obliquely backwards in a straight line to the 

 poster o-lateral angles, gradually decreasing in depth towards their distal extremities. 

 Another groove starts in the anterior third of the carapace from each of the branches 

 and runs transversely outwards to the lateral margin ; from each transverse groove a 

 short branch runs forwards to the middle of the orbit. In the posterior two-thirds 

 of the carapace, parallel to the lateral margin is a deep and very conspicuous groove, 

 anteriorly bifurcated and Y-shaped (as in D. malabar ica , D. sulcata and D. fenestrata), 



1 Pearse, Philippine Journ. Sei., VII, p. 113 (1912). 



* Alcock, Ann. Mag. Nat. Hist. (6), X, p. 415 (1892). 



6 Nobili, Boll. Mus. Torino, XVIII, No. 452, p. 20 (1903). 



