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SOME LAND AND FRESH-WATER SHELLS COLLECTED 

 IN THE ISLAND OF BOMBAY. 

 By A. J. Peile, R.A. 

 {Read before the Bombay Natural History Society on 18th March, 1897.) 



The object of this paper is to give an account of the land and fresh- 

 water Mollusca already collected in Bombay which will enable col- 

 lectors to name their specimens, and also to draw the attention to this 

 branch of Natural History of those who generally look on the " snail " 

 as an annoying visitor to the garden. It does not take any notice ol 

 species, however common, that have not been found in the island itself; 

 and the descriptions, it is feared, will not be elaborate enough to 

 distinguish some of the species from others closely resembling them to 

 be found in other localities. This, in many cases, can only be done by 

 comparison with a good collection— -a thing that the Society should 

 have, and for which the co-operation of .members is asked. 



The species described are fairly typical of those to be found all 

 over India. 



The land Mollusca are particularly interesting to the Naturalist, as 

 affording evidence of geographical distribution, and also on account of 

 their extremely interesting and varied shapes. 



The fresh-water Mollusca, on the other hand, show prevailing 

 forms very widely distributed. 



A very convenient way to divide our species for the purposes of 

 classification is into operculate and inoperculate. This, to all intents 

 and purposes, separates them into two natural orders to which they as 

 univalves belong, viz., Prosobranchiata and Pulmonata. To the first 

 of these two orders belong also a number of the marine Mollusca, some 

 of which are operculate and some not, such as whelks and cowries. 

 The land and fresh-water families belonging to it are all operculated. 



The land families, while resembling the other members of the 

 order in many points of their anatomy, have the ctenidium, or breath- 

 ing organ, replaced by a pulmonary sac to enable them to breathe air. 



The families belonging to the second order, the Pulmonata, are 

 almost without exception inoperculate and breathe by means of a 

 pulmonary sac. Whether all the fresh-water members rely altogether 

 on this sac for their air-supply seems uncertain. The animals are 

 hermaphrodite, whereas in the first order the sexes are distinct. 



