Extinction, of Organic Beings. 479 



ing or modifying a species, how is it that " Nanina vesicula," 

 so widely distributed through the provinces, still remains 

 precisely the same in habits, form, and economy, even on a 

 mountain rising to the height of nearly eleven thousand feet 

 above the sea, and where snow lies early in autumn, and 

 continues throughout the winter season, even till the end 

 of May ? 



Or, why, since the rigours of a cold climate are known 

 to be instrumental in clothing the animals of warmer regions 

 with a thicker and more woolly covering, has it not altered 

 the habits and economy of these fragile beings ; for we find 

 Nanina vesicula using the same thin vicid operculum, and 

 in every respect preserving the same habits on Huttoo moun- 

 tain, in the Himalaya, as it does in the hot plains of the Gan- 

 getic provinces ; and two other species, the " Nanina mon- 

 ticola," (Nob.) and " Pupa sylvatica" (Nob.) which I disco- 

 vered among juniper bushes at the Burrenda Pass, on the 

 Snowy range, make use, at the height of between thirteen 

 and fourteen thousand feet, on the verge of never melting 

 snows, of the same means to secure the aperture of their 

 shells, as their congeners whieh inhabit the lower and 

 warmer ranges near Simla ? 



It is obviously because a merciful Creator originally en- 

 dowed these species with constitutions to set the effects of 

 climate at defiance, and to preserve themselves distinct and 

 free from change or modification, alike among the snows of 

 a mountain winter, or the burning heats of a tropical summer. 



But again, if we wander with these several species from 

 the original focus of creation, how shall we cross the many 

 streams and rapid rivers (to say nothing of the sea) which 

 intersect and divide the various countries in which they 

 are found ? 



Or, how, since rivers in different quarters of the world are 

 stocked with species peculiar to themselves, could they have 

 wandered to their respective localities ? 



