167 



at one time flooded and at another dry. In addition to a pair of pectinate 

 gills to which the water passes through a lateral tubular fold of the 

 mantle, there is also a pulmonary sac or lung for breathing air. This 

 peculiarity, observed originally by Mr. Guilding at the Caribbee Islands, 

 was noticed first in detail by M. Caillaud on his return from his expedi- 

 tion to the Nile. It is related by him, that when unpacking in Paris a 

 box of Ampullarice, which he had collected four months before in one of 

 the tributaries of the Nile, he threw the specimens into a basin of water 

 to get rid of their offensive smell ; when great was his surprise to see some 

 of them crawl forth alive. The Ampullarice are, however, water-animals 

 rather than land, the power of respiring through a lung being only a 

 temporary faculty sufficient for the mollusk to survive the occasional 

 drying-up of its more natural element. In 1827, when M. d'Orbigny 

 had collected together at Buenos Ayres some Ampullarice found near the 

 mouth of the river Plata, he tried an experiment with the view of testing 

 the observations which had been made on this subject some few years 

 before in the West Indies by Mr. Guilding. Some of the specimens 

 which he kept alive out of water lived eight months and others thirteen 

 months. Many of the Ampullarice inhabit rivers, but not in parts where 

 there is any rapid flow. Although the shells are mostly of a sombre 

 olive-green colour, the soft parts are often prettily striped and dotted. 



The genus furnishes half-a-dozen well-marked subdivisions : A. fasciata 

 [Ampullaria proper) ; A. scalaris (Potmis, Humphrey) ; A. cornu-arietis 

 [Ceratodes, Guilding) ; A. megastoma [Pomella, Gray) ; A. Botteniana 

 [Lanistes, De Moutford) ; A. Plata {Ampulloidea, D'Orbigny), the last 

 not having the respiratory tube. 



So many new species of Ampullaria have been collected by recent tra- 

 vellers in comparatively few localities, that it is more than probable the 

 genus abounds to a much larger extent than we have at present any idea 

 of. It does not, however, exist in the great rivers of North America or of 

 north-temperate Europe, and is peculiar to warm and tropical latitudes. 



Species. 



1. adusta, Reeve. 10. Bridgesii, Reeve. 19. Columbiensis, Sowerhj. 



2. Araazonica, id. 11. buxea, id. 20. compacta, Reeve. 

 3.ampullacea(i?e/u , )Lin.l2. caliginosa, id. 21. complicata, id. 



4. aperta, Philippi. 13. canaliculata, Lamarck. 22. conica, TFood. 



5. auriformis, Reeve. 14. carinata, Swaiuson. 23. cornucopia, Reeve. 



6. aurostoma, Lea. 15. Cassidiformis, Reeve. 24. crassa, Swaiuson. 



7. balanoidea, Gould. 16. cerasura, Hanley. 25. Cubensis, Reeve. 



8. bilineata, Reeve. 17. cinerea, Reeve. 26. Cumingii, King. 



9. bulla, id. 18. citreum, id. 27. cuprina, Reeve. 



