149 



Family III. HELICID^E. 



BODY long and spirally coiled : mantle covering the front 

 or anterior part : tentacles nearly always 4 (rarely 2 only), 

 retractile : eyes placed on the tips of the upper or single 

 pair : foot oblong, distinct from the rest of the body. 



SHELL spiral, and in almost every case capable of con- 

 taining the whole body. 



This family comprises the true Snails, and abounds in 

 species as well as individuals. L. Pfeiffer described no 

 less than 1149 species of the typical genus, Helix, in 

 1848, when his very serviceable Monograph on this 

 family was published ; and if we add to this list the re- 

 sult of subsequent discoveries or reputed novelties, as 

 well as all the species of Bulimus and other allied genera 

 (which scarcely differ from Helix, and are only considered 

 distinct for the sake of more easy classification), we can 

 form some idea how exceedingly numerous this family 

 is. Strictly speaking, it only consists of one genus, like 

 TestacellidcB', and there is rather a generic than a family 

 resemblance amongst its members. The chief points of 

 difference between the genera of the present family are, 

 that in Succinea the body is ordinarily a trifle larger 

 than the shell ; in Vertigo the two lower or smaller ten- 

 tacles are wanting ; in Clausilia the shell has a reversed 

 spire, and is furnished inside with a small moveable pro- 

 cess ; in Bulimus, Pupa, and Balia the spire is longer, 

 and in the last-mentioned genus reversed ; while in 

 Cochlicopa and Achatina the spire is more produced and 

 the mouth of the shell is channeled or notched at its base. 

 But without some artificial classification of this kind the 

 genus Helix would be too unwieldy ; and the division 

 into subgenera is generally considered inconvenient, be- 

 cause it occasions additional and unnecessary nomen- 



