DISPERSAL BY MAN, 227 



water shell which Inhabits the Danube, was once found, 

 according to Mr. Jeffreys, in the bottom of a fishing- 

 boat at Cullercoats, Northumberland.^ 



Of terrestrial species, the Conchological Society's 

 list (1883) contains the names of eighty-six species, of 

 which but three, Testacella uiaugei, Helix villosa, and 

 Bulimus goodallii can be reasonably looked upon as 

 introduced by human agency ; and two of these names 

 {Helix viiiosa and Buliiiuis goodallii) are included within 

 brackets, showing that the creatures' claims to be re- 

 garded as British were not considered to be established, 

 and Helix villosa is known to have been placed in the 

 catalogue on the faith of a colony which is now extinct. 

 That the terrestrial molluscan faunas of the world have 

 been much more influenced by man's dispersal than 

 fresh-water faunas cannot be doubted, but this hardly 

 seems to have been the case in our own country. It may 

 be remarked, however, that the indigenousness of at least 

 six species (in addition to the three above mentioned) 

 has been questioned by various authors, and other 

 authors have probably doubted the right of still other 

 species to rank as native. The evidence which can 

 be got together does not, as far as I am acquainted 

 with it, warrant the conclusion that any of these have 

 certainly been Imported, but it is of course possible that 

 this may have been the case with some of them. Of 

 the three species generally regarded as introduced, 



* Jeffreys, "British Conchology,'' i. (1862), p. 70. 

 Q 2 



