■ and Marine Molusccs. S^ 



3. This power of accustoming themselves to live in a 

 liquid of a very different degree of saltness from that in 

 which they usually exist, is not the same in all moluscse. 



Thus, among the fresh -water moluscae, the bivalves (auo- 

 donta;, unio, and cyclas) could not live in water that had 

 acquired the saltness of the sea — (0.04.) 



Among the marine moluscae, the patellae, the fissurellae, 

 ihe crepidulae, the pectens, the limae, &c. could not accus- 

 tom themselves to live in fresh-water. 



4. All moluscae, whether marine or fresh-water, can 

 easily be made to live in water about half as salt at that of 

 the sea, that is, containing only two parts of muriate of soda 

 in a hundred of salt-water. 



5. Fresh-water moluscae could not in any manner be 

 accustomed to live in water charged with sulphate of lime. 



The author presumes that it is the same with marine mo- 

 .luscas ; he has not however put them to this test. 



6. Marine moluscae can live in waters much more charged 

 with salt than those of the sea usually are, even when the 

 water is saturated with it ; they perish however when the 

 liquid is over saturated, and a deposit of salt commences. 

 M. Beudant made some experiments with water charged 

 with carbonic acid, mineral acids in small quantities, or with 

 0.02 of sulphate of iron ; he plunged fresh-water molusc£e 

 suddenly into it, and they all died immediately. 



The author acknowledges that it would be desirable to 

 .repeat and execute his experiments on a greater scale ; yet 

 he remarks that he has tried a number of individuals and a 

 great variety of species, and he observes, that having experi- 

 mented with vases of a small capacity, and generally under 

 circumstances not very favourable io the change of element 

 to which he would submit the moluscs, it is more than pro- 

 of an equal number kept in salt-water frequently renewed, 34 in 100 

 died in the same time. 



The author finished by placing, at the end of summer, the marine 

 moluscs, thus habituated to fresh-water, into a piece of water in a gar- 

 den, where they were still living in company with lymneae and other 

 fresh-water moluscs, at the end of the following April. 



