igiô.] 



Fauna of the C h ilka Lake ; Mollusca Gastropoda, etc. 



3-U 



the Mala}?" Archipelago, the Andamans and the Maldives, is perhaps a casual visitor, 

 but the shell may have been brought from the sea by a hermit-crab. 



Nassa denegabilis, Preston, 1914, p. 297, fig. 9; 1915, pp. 290, 480; I9i6,p. 28. 



This species occurs all over the lake-system on a bottom of mud or muddy sand . 

 The type, which was named, but not described by the late Mr. G. Nevill, is in the 

 British Museum. N. denegabilis is found at all times of the year in an active condi- 

 tion. The species is evidently common in estuaries and backwaters on the Indian 

 coasts. 



Nassa orissaënsis , Preston, 1914, p. 299, figs. 10, 10a ; 1915, p. 290. 



This is perhaps the commonest and most widely distributed Gastropod in the 

 main area and in the inner part of the outer channel , occurring on a muddy bottom 

 usually among weeds. When placed 

 in a dish of water, specimens often 

 float shell downwards adhering to 

 the surface film by means of the ex- 

 panded foot. The foot does not 

 conform to the description of the 

 genus given by Fischer l , for the two 

 posterior lobes, instead of being pro- 

 duced and pointed, are very short, 

 broadly rounded and separated 

 merely by a shallow notch (see fig. 

 1). This peculiarity may be cor- 

 related with the softness of the mud 

 on which the animal frequently 

 crawls. We are under the impres- 

 sion that the foot of N. denegabilis 

 is similar, but have no definite note 

 on the subject. 



N. orissaënsis is represented in 

 the Madras backwaters and in canals of brackish water at Calcutta by a large and 

 well-developed variety (var. ennurensis, Preston, Rec. Ind. Mus., 1915, p. 479; 1916, 

 p. 28, fig. 2). 



Family Muricidae. 



Thais carinifera (Lam.), Reeve, Conch. Icon., Ill, Purpura, pi. vi, fig. 26 (1845). 



In the main area of the lake this species is confined to the rocks at the southern 

 end and to the islands south of Kalidai. It was also found in the outer channel in 

 the salt-water season, but was apparently unable to live in pure fresh water and is not 

 found on the rocks near Patsahanipur. On the oyster-beds at Manikpatna it is fairly 

 abundant in March, but in other places is usually found crawling on rocks. A few 



cl. à. 



Fig. 1. — -Nassa orissaënsis, Preston. 



Living specimens : a, from above : b, from below. 

 (From sketches made by Mr. G. M. Henry.) 



Manual de Conchyliologie, p. 633, fig. 389, Paris, 1887. 



