96 OBSERVATIONS ON THE BRITISH 



lacustris, amnica, and appendiculata, — River Avon ; Helix arLusto- 

 rum, H. ericetorum, — at Newbold lime quarries (blue lias lime- 

 stone) ; Limneus scaturiginum^ — River Avon. So that we have 

 thirty-eight species common to both places — five in the former are 

 not met v^rith in the Rugby district, and seven of the latter place 

 are not found at Congerstone. I may, perhaps, here take the op- 

 portunity of mentioning, on the authority of Mr. Churchill Babing- 

 ton, of Thrinkstone, that the CarocoUa lapicida is found at Grace- 

 dieu, in this county ; and I have also met with Helix arbustorum 

 and radiata, Clausilia rugosa, Bulimus obscurus, Achatina acicula, 

 and Pupa umbilicata, about twelve miles from hence, in the neigh- 

 bourhood of Calke Abbey, Derbyshire ; to which place I also trans- 

 ferred about three years ago, a colony of Helix pomatia (sent from 

 the neighbourhood of Hertford), which, I believe, is still flourishing. 

 This is the edible snail of the continent, and the largest of our diffe- 

 rent species of Helix. As an account of its peculiar operculum may 

 not perhaps be unacceptable to some of your readers, I will conclude 

 these desultory remarks with an extract from Turton's work above- 

 mentioned. 



'' In the winter, the mouth is closed by a thin calcareous lid, or 

 epiphragm, which, however, is not attached to the inhabitant, like 

 the true operculum of the Cyclostoma and Paludina ; but, having 

 performed its office of protection from severe cold, is dissolved upon 

 the approach of summer, — not by the increased heat of the atmos- 

 phere, — but by a phosphorous acid, which at that season it abun- 

 dantly secretes. In the first vol. of The Zoological Journal, at p. 99^ 

 Mr. Gaspard supposes that the epiphragm seals up the mouth her- 

 metically during the winter; and that, in this state, the inhabitant 

 is without animal heat, nutrition, respiration, or circulation, and 

 utterly devoid of all animal organic formation ; observing in testi- 

 mony, that they may be immersed in water during the winter, and 

 yet recover themselves in the spring. This would suppose, not only 

 the utter extinction of vital existence and actual death, but an an- 

 nual reviviscence and regeneration of life — a doctrine quite at vari- 

 ance with our knowledge of the laws of physiology, as applicable to 

 animated nature. But upon examination it will appear that, in the 

 centre of this epiphragm, is an exceedingly minute orifice, commu- 

 nicating with an umbilical chord which is connected with a fine 

 placenta-like tissue of vessels, penetrating into the pulmonary cavi- 

 ty itself; and this minute orifice, although not large enough to ad- 

 mit a drop of water, is of sufficient capacity for the passage of that 

 quantity of oxygenated air, necessary for the purposes of extremely 



