HELIX. 185 



In this, the spire is more elevated, and sometimes has 

 six full volutions. There is a deep groove behind the 

 lip, contracting the aperture ; the lip is widely reflected, 

 and directed inwards, forming a basin-shaped mouth ; 

 the upper labial tooth is broader, sometimes bifid, and 

 even trifid, and very much inflected ; the columellar 

 tooth extends quite to the base of the shell, and unites 

 with the extremity of the lip ; the aperture is nearly 

 filled uj) by the teeth and the contraction of the lip. If 

 this variety were to be seen alone, it would be adjudged 

 to be a good species, and is generally so considered. 

 Having examined a great number of every variety, from 

 numerous localities, I have found every gradation be- 

 tween the extremes, and am convinced that they form but 

 one species. The animals do not dlfier in the least degi-ee. 



Helix tridentata resembles Helix palliata on its upper 

 surface, but diSers fi-om all others. The situation in 

 which I have most commonly found it, is under the 

 layers of wet and decaying leaves in forests ; it is also 

 found under flat stones. I have one specimen in which 

 the direction of the whorls is reversed. 



The figure of F^russac represents a very small shell, 

 probably the southern variety. Lister's figure, tab. 92, 

 figure 92, is probably intended for this shell. 





47 



