122 Records of the Indian Museum. [Vol. XV", 



already described by various malacologists. The difference observed 

 between the three genera and others consists mainly in the relative 

 position of the different organs, a remarkable point being the arrange- 

 ment of the various loops of the intestine which are practically 

 identical in four species described here. Further, the main differences 

 in general structure between the three genera described here are only due 

 to the elongation of the body in the antero-posterior direction, this being 

 greatest in Solenaia and least in Physunio, with LamelUdens occupying 

 an intermediate position between the two. Considering the individual 

 organs, it is important to note that in Solenaia all the four gills seem 

 to give rise to ovisacs, and the kidneys also are more complicated than 

 in the other two, somewhat resembling those of Aviodonta. 



Reference. 



1. Lloyd, R. E. — An Introduction to Biology, 1910. Longmans, Green 



& Co. 



2. Marshall and Hurst. — Practical Zoology, 1905. Smith, Elder & 



Co., London. 



3. Ortmann. — Mem. Carnegie Museum, Pittsburg, Pa., Vol. 4, 1911, pp. 



279-347. 



4. Pelseneer, p. — Mollusca, in Lankester's Treatise on Zoology. 



