DISPERSAL BY MAN. 25 1 



tidea as a variety : the aggregate has a fairly wide 

 range in this country, and the creatures sometimes 

 occur in large numbers, but it appears that T. haliotidea 

 proper is less common than T, scuttilum^ for, according 

 to the Leeds "Census" (1889), the latter has been seen 

 by the Conchological Society's referees from thirteen 

 counties, and the former from only eight.' 



The following molluscs, probably among many 

 others, all exotic, have been detected in Britain, either 

 in a living state or as dead-shells. Some have been 

 found alive in open places, like true members of our 

 fauna, and several have actually been admitted, at one 

 time or another, into the British lists. Most of them 

 have almost certainly been imported by man, no doubt 

 for the most part unintentionally. 



Helix limbata Urap., the " white-keeled snaiP' of 

 Gray's " Turton," a native of the south of France, etc., 

 is said to have been found in the neighbourhood of 

 London by Mr. G. B. Sowerby, and was introduced 

 into our catalogues, in 1837-8, by Mr. Alder, who had 

 received specimens from Mr. Sowerby. Gray included 

 it in his '^Turton " of 1840, stating, on Mr. Sowerby's 

 authority, that it lived *' in the hedges near London, on 

 the New North Road to Barnet, near Hampstead, on 



' Gray's "Turton," 1840, p. 4; 1857, p. 291; "Jeffreys," i. 

 (1862), p. 146; "Rimmer," 1880, pp. 88-9; Joshua Alder, " Ma^. 

 Zool. and Bot.," ii. (1838), p. 105; on the specific distinctness and 

 geographical distribution of T. scutuluin, see J. W. Taylor, 

 "Journal of Conch.," v. (1888), pp. 2>V-M' 



