6i2 Records of the Indian Musemii. [Vol. XXII, 



Type-series. — No. M 1 1962/2 in the Zool. vSuiv. Ind. {Ind- 

 Mus.) 



The soft parts conform to the description of the genus given 

 already. 



The type-series was collected in the Dhanushori stream in 

 Assam. 



T. dhanushori bears some superficial reseml)laiice to T. 

 foUaceus (Gould), but differs in the comparatively more elongate 

 shell, more evenly rounded anterior margin, poorly developed 

 posterior wing and more prominent umbones. The hinge also is 

 different in the two species. 



Family CYRENIDAE. 

 Genus Corbicula, Megerle. 



This genus is represented in the collection by three species. 

 Of these C. striatella is common throughout India and Burma, 

 C. occidens has a wide distribution in the Central Provinces, 

 United Provinces, Bengal, Bihar and Orissa. vSikkini and Assam, 

 while the exact habitat of C. subradiafa was hitherto unknown. 



The only account of the anatomy of any of the Indian species 

 is contained in a recent pap;r ' Vjy myself on the soft parts of 

 C. fluminalis — the type-species of the genus. The soft parts of 

 the three species here discussed are very like those of C. flu))iinalis ; 

 the differences from it are included in the notes on the different 

 species. 



Corbicula occidens, Deshayes. 



1854. Corbicula occidens, Deshayes, Cat. Brit. Mus. Concliifera, p. i-ii,. 

 igoo. Corbicula occidens, Preston, op. cit., p. 2l(i. 



The range of distribution of the species according to Preston 

 is "Sikkim, Moradabad, Bengal," but in the collections of the 

 Indian Museum there are specimens from various places in the 

 Central Provinces, Bihar and Oiissa, and Assam in addition to the 

 localities given by Preston. 



The only point of interest to note in connection with the 

 shell is the slightly discontinuous pallial line. The line runs down 

 as a vertical straight line from the lower edge of the impression of 

 the posterior adductor muscle, and this part forms a little more 

 than a right angle with its horizontal continuation forwards to the 

 scar of the anterior adductor muscle. This condition is a little 

 more advanced than that in C. largillicrti figured by Prime '^ and 

 is correlated with a better development of the siphonal muscles. 



The soft parts generally resemble those of C. fluminalis 

 described in the paper cited, but diifer in having the siphonal 

 muscles, the siphons and the foot a little better developed, in the 

 inner pair of gills being much broader (about one and a half times) 



1 Rec. Ind. Mus. XVIIl, pp. 209-211 (1920). 



■' Ann. Lyceum Nat. Hist. A'. York VIII, d. 4.20, fig. 4 (1867). 



