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



Unfortunately several changes in nomenclature, affecting both genera and species, 

 have been rendered necessary by further investigations undertaken since the publica- 

 tion by Dr. Kemp and myself of our report on the Mollusca in this volume (1916). 

 These changes I will explain in footnotes. 



Gastropoda. — Two of the species found in Rambha Bay in 1914, Cuthona henrici 

 Eliot (fam. Aeolidae) and Litiopa kempi Preston (fam. Litiopidae) were of such rare 

 and sporadic occurrence that they need not be considered further. Neither was 

 found in 1919-20. At the end of this paper Dr. Baini Prashad and I describe a 

 Nudibranch mollusc of the family Hermaeidae discovered in the bay in June, 1920. 



The Opisthobranchia, apart from the Cuthona, were represented in 1914-15 by 

 a single species (Tornatina estriata Preston, fam. Tornatinidae). This in 1914 

 was one of the commonest molluscs all over the lake. In August, 1919, I dredged 

 numerous dead shells of this species, especially between Cherriakuda and the main- 

 land. Among them I found two exceptionally small living individuals. In Septem- 

 ber and December of the same year I still found dead shells, but no living speci- 

 mens, and in April, 1920, even empty shells seemed to have disappeared. 



The Nassidae are represented in the bay by two very abundant species, Nassa 

 denegabilis and N. orissaensis Preston. These were among the most abundant mol- 

 luscs in 1914, and in 1920 showed no marked diminution in numbers. 



By far the largest living gastropod in the main area of the lake in 1914 was a 

 species (Cuma disjuncta) closely allied to C. carinifera (Lamarck) 1 of the family Muri- 

 cidae. It was not uncommon on the landing-stage at Barkuda and among the rocks 

 at the base of Ganta Sila, where the egg- capsules were found in February. Subfossil 

 shells are still abundant on the shore at Barkuda but living individuals have com- 

 pletely disappeared. 



The Cerithiidae, though many species live in brackish water, were represented in 

 191 4 in the main area of the Chilka Lake by a single species, Potamides cingulata 

 (Gmelin) 1 . This species was found living at only one spot in Rambha Bay, viz. in a 

 ditch at Rambha. I have not been able to find it at this spot recently, but con- 

 siderable changes have been made artificially in the ditch. 



A small elongate shell from Rambha Bay, the true systematic position of which 

 s still somewhat doubtful, was placed in the genus Vanesia and the family Turri- 

 tellidae by Preston. Living specimens were found, occasionally in some abundance, 

 in 1914. In 1919-20 only dead shells were obtained. 



Preston recorded four species of the genus Stenothyra (family Hydrobiidae) as 

 occurring in Rambha Bay. A re-examination of his material has convinced Dr. 

 Baini Prashad and myself 3 that great confusion prevails in his identifications. 

 We believe that the following species actually occurred in the Bay in 1914. Steno- 



' Identified by Preston as Thais carinifera, but really distinct. I have described it in the Memoirs 

 of the Asiatic Society of Bengal VII, pp. 266-8, fig. 2 (1922). 



* Named Potamides (Tyfanotonos) fluviatilis Pott, and Mich, by Preston. The name given above 

 seems to be the correct one, as Dr. Baini Prashad has demonstrated to me. 



s Annandale and Prashad, Rec. Ind. Mus. XXII, pp. 121-136, pi. xvi (1921). 



