Land-snails 



349 



and becomes no more important than Claiisilia. In 

 these pages we have kept the genus intact. 



The Dwarf Snail {H. 'pygmcta) is the least of the 

 British species, and one that does not fall into the 

 hands of the collector who has little patience. More- 

 over, the lens is required for its examination when 

 obtained, to make sure that the specimen is not the 

 young of another species {H. riipestris), which is also 

 very small, but twice the size of |;?/r/}na^rt. The 

 Dwarf's shell is circular, flattened from above and 

 l)elow, consisting of four whorls, and measuring one- 

 sixteenth of an inch across. It is very thin, light 

 brown, with a silky gloss; the spire but slightly 

 raised, the umbilicus large, and exposing the whole 

 interior of the spire ; mouth horseshoe-shaped, without 

 an internal rib. The animal is brown or grey, 

 minutely dotted with black. It chiefly affects woods, 

 where it lurks under stones and dead leaves during 

 the daytime. The knowledge that it is found in a 

 particular wood may be utilised by the collector with 

 limited time, if he will follow Dr. Turton's plan : 

 collect a bagful of moist dead leaves, and on reachint*- 

 home spread them to dry on an open newspaper : 

 the snails can then be sifted out easily. It is a 

 widely distributed species. 



The Rock Snail {H. rujx^stris), which resembles the 

 last somewhat, attains a diameter of one-seventh of 

 an inch. The shell has Ave whorls, is of more solid 

 material than that of //. 2)yg^n(^t'('^ and has a deeper 

 suture — that is, the slight trench separating one 

 whorl from another. It is also less flattened above, 

 of a darker brown, and the whorls are crossed by fine 

 lines. It inliabits the crevices of rocks and walls in 



