XIX. STUDIES ON THE ANATOMY OF 

 INDIAN MOLLUSCA. 



3. The soft parts of some Indian Unionidae. 



By B. Prashad, D.Sc, Officiating Director of Fisheries, Bengal, 

 Bihar and Orissa, Calcutta. 



Ortmann ' writing in igir about the glochidia of the Unionidae 

 summed up in the following sentence, " I have no doubt that this 

 finall}^ will be a very important systematic criterion, but unfor- 

 tunately we do not know the glochidia of a single Asiatic species." 

 Since then I have in two papers'^ described the structure of the 

 marsupia and glochidia of the Indian genera Physunio, Parreyssia, 

 Lamellidens and Indonaia. The results of my work have amply 

 justified Ortmann's criticism^ of Simpson's classification,* in which 

 shell-characters alone were utilised to a large extent for the 

 classification of the Naiades. On studying the soft parts of the 

 animals of the genera Physunio, Lamellidens, Parreyssia and 

 Pseudodon it was found that the position assigned to those genera, 

 from shell-characters only, was quite wrong, while two new genera 

 Indonaia and Balwantia had to be established for the Indian 

 species hitherto included in the genera Nodularia and Solenaia 

 respectively. 



In my second paper I included a description of the soft parts 

 of the animal of Indonaia, but refrained from discussing these 

 in the other genera as Dr. Ekendranath Ghosh was engaged in a 

 study of the comparative anatomy of some of the forms. His 

 results, however, which were published in a recent paper/ are far 

 from complete from the point of view of the systematist and many 

 important details are neither mentioned in the text nor shown in 

 the figures. In the present communication I have, therefore, tried 

 to ratify these omissions for the genera dealt with by Ghosh, and 

 have in addition given descriptions of the animals of the genera 

 Parreyssia and Pseudodon. In deaUng with the various genera I 

 have discussed their position in both Simpson's and Ortmann's 

 classifications, and at the end of the paper I have given a key for 

 the identification of these genera based on the soft parts of the 

 animals. 



1 Ann. Carnegie Mus., VIII, p. 239 (1911-12). 



•' Rec. Ind. Miis., XIV, pp. 183-185, pi. xxii (1918), and ibid.. XV, pp. 143- 

 149 (1918). . 



3 Mem. Carnegie Mus., IV, pp. 279-347- P^s- Ixxxvii-lxxxix (1911). 

 * Proc. U.S. Nat. .Mus , XXII, pp. 501-1075 (1900). 

 s Rec. Ind. Mux., X\', pp. 109-123, pi. xvi (1 91 8). 



