374 



GEOGRAPHICAL DISTEIBUTION AND 



[Ch. XL. 



CH' 



foundland and parts of North America. It was found by 

 Captain Hutton in Afghanistan.'^ As this animal inhabits 

 constantly the borders of pools and streams where there is 

 much moisture, it is not impossible that different water- 

 fowl have been the agents of spreading some of its minute 

 eggs, which may have been entangled in their feathers. The 

 freshwater snail, Lymneus palustris, so abundant in English 

 ponds, ranges uninterruptedly from Europe to Cashmere, and 

 thence to the eastern part of Asia. Helix aspersa, one of 

 the commonest of our larger land-shells, is found in St. 

 Helena and other distant countries. Some conchologists have 

 conjectured that it was accidentally imported into St. Helena 

 in some sliip ; for it is an eatable species. 



As an illustration of the power of such moUusca to retain 

 life during a long voyage without air or nourishment, I may 

 mention that four individuals of a large species of landshell 

 {BuUmus)y from Valparaiso, were brought to England by 

 Lieutenant Graves, who accompanied Captain King in his 

 expedition to the Straits of Magellan. They had been packed 

 up in a box, and enveloped in cotton : two for a space of 

 thirteen, one for seventeen, and a fourth for upwards of 



Mr. 



twenty months : but when they Avere exposed 

 Broderip to the warmth of a fire in London, and provided with 

 tepid water, I saw them revive and feed greedily on lettuce 

 leaves. 



Perhaps no species has a better claim to be called cosmo- 

 polite than one of our British bivalves, Saxtcava rugosa. It 

 is spread over all the north-polar seas, and ranges in one 

 direction through Europe to Senegal, occurring on both sides 

 of the Atlantic ; while in another it finds its way into the 

 North Pacific, and thence to the Indian Ocean. Nor do its 

 migrations cease till it reaches the Australian seas. 



A British brachiopod, named Terehrahda caput serpeniis^ is 



to Professor E. Eorbes, to both sides of 



common 



» 



North 



seas. 



Node of diffusion of Testacea. — Notwithstanding the pro 



* J. Gwyu Jeffreys; British Concliology, p. 152. 





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