INDEX. 



271 



on the wide distribution of 

 freshwater shells, 4. 



on the dispersal of freshwater 

 organisms, 29. 



on the difference in the distri- 

 bution of freshwater and 

 land shells, 29, 97. 



on changes of level, 30, 117. 



on salt-water killing snails, 

 40. 



on fish carried by whirlwinds, 



43- 



on the dispersal of eggs of 

 freshwater shells, 46. 



experiment with a duck's feet 

 in an aquarium, 49. 



on shells carried with duck- 

 weed, 51. 



on earth adhering to birds, 54, 

 158. 



on bivalves clingnig to water- 

 beetles, 63, 64. 



on the flying habits of water- 

 beetles, 66, dl^ 69. 



on their carrying powers, 67. 



on a Unio clinging to a teal, 

 80. 



on dispersal by birds, 82, 156, 

 177. 



on an Ancyliis adhering to a 

 Dytisacs, 87. 



on wide ranges, 95. 



on changes of climate, 117. 



on hypothetical continental 

 extensions, 118. 



on dispersal by ocean currents, 

 120. 



experiments with snails and 

 sea- water, 120. 



on dispersal by icebergs, 123. 



on floating timber, 126, 128, 



135. 



on dispersal of the young of 

 land-snails, 157. 



on organisms carried in birds' 

 crops, 159, 162. 



on dead birds floating on the 

 sea, 163. 

 Darwin, F., on C. Darwin's expe- 

 riment with a duck's feet in 

 an aquarium, 49. 



on mussels clinging by closure, 



58. 

 Davy, J. B., on isolated ponds, 11, 



12. 

 on bivalves clinging to frogs, 



74- 

 on Physa acuta at Kew, 225. 

 Denbighshire, shower of hay in, 



153- 



Denmark, attempted colonization 



oi Helix poinatia in, 187. 

 Descent, monophyletic, i. 



polyphyletic, 3. 

 Dickens, an allusion to wind- 

 dispersal by, 154. 

 Digby, Sir K., said to have im- 

 ported Helix pomatia, 235. 

 Dikes, W. H., shells in a bird's 



crop, 160. 

 Dispersal, of freshwater shells, 27. 

 of bivalves while clinging by 



closure of their valves, 56. 

 of operculates while clinging 

 by closure of the operculum, 

 85, 165. 

 of freshwater univalves while 

 adhering to other animals, 

 86. 

 of land-shells, 95, 115. 

 scarcity of evidence of, 119, 



172. 

 habitats conducive to, 34, 37, 

 52, 132, 140, 146, 169, 171, 



173- 

 of slugs, 167. 

 Dispersal by man, 156, 178, 209. 

 Distribution, local, i, 5, 23, 82, 94, 



164. 

 discontinuous ranges, 2, 92, 



173- 

 freshwater shells absent from 



some oceanic islands, 93. 

 reasons for the differences in 



the distribution of freshwater 



and land shells, 95. 

 small snails, and operculates, 



range more widely than large 



inoperculate snails, 136. 

 Distribution of freshwater species, 



wide, 4. 

 of land species, restricted, 90. 



