igiQ-l B- Prashad : The Anatomy of Indian Mollusca. 291 



attachment is rather short. The foot is very large and has a well 

 developed musculature. The mantle has a very much thickened 

 entire margin ; near the branchial aperture it has a few papillae 

 developed on its edge. The branchial aperture is large, with two 

 to three rows of large conical papillae ; its margin is of a yellowish- 

 brown colour. The anal aperture is about half the size of the 

 branchial ; it is quite smooth and much lighter in colour. 

 Separating the branchial from the anal is a well-developed ridge of 

 the mantle , in the living animal the ridges of the opposite sides, 

 meeting each other in the middle, would form a continuation of the 

 diaphragm and completely separate the branchial from the anal 

 aperture. The supra-anal is slightly larger than the anal, while 

 the mantle connection between it and the anal is much larger than 

 either. 



The glochidium (fig. 2) may be said to be suboval in outline, 

 with a nearly straight hinge line. It measures "26 mm.X"2i mm. 



Systematic position : — The species was originally described 

 b}^ Benson * as Anodonta soleniformis. 

 Lea * considered it to be a Margaron 

 and redescribed it as M. {Unio) ben- 

 soni. Hanley and Theobald,^ dif- 

 fering from both authors, included 

 it in the African genus Spatha. Fis- 

 cher * after an elaborate discussion ,^ .,, ,.,. , „ , 

 J. ^ ' 11-, • • 1 •. . Text-fig. 2. — (jlochidium of /?(?/- 

 of the whole situation, assigned it to ^^antia solenifonnis, x 75. 

 the genus Mycetopus. Simpson ^ in 



his monograph separated it from the genus Mycetopus and included 

 it, with a number of species from China, Siam, South Eastern Asia 

 and a doubtful one from Australia, in the genus Solenaia. Preston * 

 has, following Simpson, described it as S. soleniformis (Benson); 

 some of his references to the previous works, however, are in- 

 correctly cited. The animal of the Indian species is quite different 

 from that of a species of Solenaia described by Fischer {loc. cit., 

 p. II). I have, therefore, found it necessary to separate the only 

 known Indian species as a new genus, for which the name Balwantia 

 is proposed. 



Simpson was right in including the species in the sub-family 

 Unioninae and in the group Exobranchiae, but made a mistake in 

 assigning it to the subgroup Homogenae, because, as has been 

 described above, this species carries the glochidia in all the four 

 gills and should be placed amongst the Tetragenae. Following 

 the later and more natural classification of Ortmann {loc. cit., pp. 

 224-225) the genus will be placed in the family Unionidae,Swainsion, 

 as restricted by Ortmann, and in the sub-family Unioninae. 



' Jouvu. Asiat. Soc. Bengal, V, p. 750 (1836). 



2 Lea, Syn., p. 57 (1870). 



^ Conch. Ind., p. 5, pi. ix, fig", i (1876). 



* Journ. Coiichvliol., XXXX'llI, pp. 11, 94 (1890). 



" Proc. U.S. Nat. Mas., XXII, p. 656 (1900). 



^ Faun. Brit. Ind., Mollusca, pp. i_^2-i34 ( 1915). 



