6o2 Records of the Indian Museum. [Vol. XXII, 



The jaw is small and has rounded extremities The cutting 

 edge is concave and is provided with a central blunt projection and 

 a subobsolete accessory projection on either side. The quadrate 

 plate is narrow and rounded posteriorly. 



The radula is fairly long and broad and has the formula 28. 

 12. 1. 12.28. The bases of the marginals are rather short and 

 concave. 



Literature. 



1. Anuandale, N., — Jaw and radula of Succinea indica. Rcc. 



Ind. Miis. XIV, pi. xi, figs. 5, 6 (1918). 



2. Binney, W. G., — On the jaw and lingual membrane of 



North American terrestrial Pulmonata. Proc. Acad. 

 Nat. Sci. Philadelphia XXVII, pp. 230-232 (1875). 



3. Cooke, A. H., — Mollusca, in Cambridge Natural History, 



I(Ondon (1895). 



4. Fi cher, P. , — Observations anatomiques sur divers Mollus- 



ques des Antilles attribues au genre Succinea. Journ. 

 Couchyliol. XXII, pp. 137-155, pi. v (1.^74). 



5. Ihering, H. von, — Ueber den Geschlechts-apparat von 



Succinea. Jahrh. Deu'. Malakozool. Ges. IV, pp. 136- 

 142 (1877). 



6. Jacobi, A., — Japanische Pulmonaten. Journ. College. Sci. 



Tokyo XII, pp. 82-85, pi. vi, figs. 116-119 (1899). 



7. Riepei, H. von, — ^tuAxen sm Succinea. Ann. Soc. Mala- 



col. Belgique XLVII, pp. 125-191, pi. iii, iv (1912). 



THE PELECYPODA. 

 By B, Prashad. 



The collection of Lamellibranchs from Manipur described in 

 the following pages is of special interest, in that most of the spe- 

 cies are represented by large series of both dry shells and speci- 

 mens preserved in spirit. This has enabled me to describe the soft 

 parts of most of the species investigated. I have also included 

 here the description of a new species of the genus Trapezoideus, 

 Simpson, collected by Mr. Sunder Lai Hora at Dimapur in Assam. 



In the collection this class is represented by the two families 

 Unionidae and Cyrenidae. Of the former, specimens of the genera 

 Indonaia, Lamellidens and Trapezoideus are represented, and of the 

 latter there are specimens of Corbicula, Sphaerium and Pisidium. 

 The most common genera in the valley are Indonaia amongst the 

 Unionidae and Corbicula and Spliaerium amongst the Cyrenidae. 



Family UNIONIDAE. 

 Genus Indonaia, Prashad. 

 1018. Indonaia, Prashad, Rec. Ind. Miis. XV, pp. 146-148, fig. 2. 

 In the Manipur Valley the genus Indonaia is represented by 

 five species. Of these /. theobaldi is apparently confined to the 



