290 Records of the Indian Museum. [Vol. XYI, 



Balwantia, gen. nov. 



Ghosh {loc. cit.) has recentl}^ described the gross anatorti}' of 

 the species Solenaia soleniformis (Benson) in a comparative wa^' 

 onl}'. Godwin-Austin and Annandale ^ have since added valuable 

 notes on the habits and burrows of the animal and this discussion 

 of the habits has brought out interesting facts about the use of 

 the very large and well-developed foot. On comparison of the 

 anatomy of the Indian species with that of the other known 

 species of the genus Solenaia, Conrad, it was found that the former 

 differs materiall}' from the others and must be separated as a dis- 

 tinct genus. The question of the name of this genus is discussed 

 at length below. 



Animal: — In accordance with the greatly elongated condition 

 of the shell, the animal (fig. i) also is drawn out in the antero- 

 posterior axis, as are organs like the gills, palps, foot, etc. 



The gills are eight to ten times as long as broad, the inner 

 pair being a little wider than the outer. The inner lamellae of 



O.G 



I.G 



Text-fig. i. -\n'nna.\ oi Balwantia soleuiformis. ^;/. ^ anal aperture ; Br, 

 = branchial aperture; /^. = foot ; /.G. = inner giil ; 0.(7. = outer gill ; P. = palp ; 

 Sit. = supra-anal. 



the inner pair are attached to the abdominal sac along more than 

 half of their anterior portion ; posteriorly the lamellae of the two 

 sides unite with one another to form the diaphragm, which extends 

 on either side up to a ridge of the mantle that separates the 

 branchial from the anal aperture. Other attachments of the gills 

 are the same as in some of the more primitive genera, viz. the 

 outer lamellae of the outer pair of gills are attached to the 

 mantle of either side, while the inner lamellae of the outer pair 

 are attached to the outer lamellae of the inner pair. All the four 

 gills are marsupial and are used for the development of the glochi- 

 dia. The free margins of the gills do not swell up when the gills 

 are filled with glochidia. The water-tubes are simple, formed of 

 17-20 gill-filaments each; the number in each gill, however, is 

 variable. The placentae are of the shape of inverted triangles. 

 The palpi are very large elongate-elliptical in outline ; the axis of 



' Rec. Iiui. Mas , X\'I, pp. 204-206 ( ujiqi. 



