54 HELICID^. 



in southern latitudes, confined to an altitude of from two 

 thousand to five thousand feet above the sea. On the 

 American continent it has been observed as far north as 

 Greenland. The most recent observations render it 

 probable that it is carnivorous. 



The type of the genus is Helix pellucida, Miiller. 

 The genus itself was proposed in 1805, by M. Drapar- 

 naud, who was the firet to see the propiiety of separating 

 it from Helix; M. F^russac soon after suggested the 

 same genus under the name of Helicoditnax. The name 

 of M. Draparnaud has universally obtained, and the 

 genus has been adopted by all the naturalists of the day. 

 Its only essential distinction, however, is the prolongation 

 of the mantle or collar into a free and unattached lobe, 

 which lies over the back, and thus resembles the mantle 

 or cuirass of the lAmaces ; it is however but a resem- 

 blance. It connects Vitrina to Limax by analogy, but not 

 by affinity ; for the uses of the organ are very different 

 from those of the true mantle oi Limax. In the latter 

 it affords a partial protection to important viscera which, 

 in this genus, ai-e much more effectually protected by the 

 sheU. Processes of the mantle, of various extent and 

 form, exist in several species of Helicidce, and without 

 doubt, differ in development m the different species of 

 this genus. Their uses are for the most part unknown, 

 though they do not seem to serve any important purpose 

 in the economy of the animal. It is not easy to see, 

 therefore, why a generic distinction, founded upon a 

 greater or less development of these parts, should be 



