OF HARTING. 313 



stumps in our woods. The Limax agrestis is the pest 

 of the farmer as well as of the gardener, and may be 

 met with in his cornfields in such abundance, that even 

 the willing pheasant finds it no sinecure to keep its 

 numbers within safe limits. 



The popular belief that slugs are only snails that, 

 for some reason best known to themselves, have tem- 

 porarily vacated their shells, is not sanctioned by the 

 observations of Malacologists, who, on the contrary, 

 have long been aware of the fact that slugs are really 

 possessed of shells of their own, of which, to put it in 

 the simplest form of language, these animals would 

 find it remarkably difficult to divest themselves. We 

 have already alluded to the prominence on the back 

 of the slug, this is the mantle on the under surface of 

 which the calcareous secrection is spread out in the 

 form of a thin plate, and the latter, from its position, 

 is no doubt designed as a protection to the important 

 organs beneath it. This plate, as may be anticipated, 

 varies in the different species, and in Testacella, a slug- 

 like animal which we have never found here, it becomes 

 external, and is situated on the back near the tail. 

 Intermediate between the slugs and true snails we 

 find the Vitrina pellucida, in which the general form 

 of the slug is associated with the spiral shell of the 

 snail. Among the decaying leaves under the beech 

 in the Park, among damp moss in the covers and 

 hedgerows, we have found this species in a state of 

 activity when nearly all the other molluscs are in 

 their winter quarters, although its thin greenish trans- 

 parent shell is much too small to contain the whole 

 body of the animal. Our largest specimen of this 

 pretty shell is about a quarter of an inch across. 

 The Cellar Snail (Helicella Cellaria], shell a pale 

 horn colour ; the Garlic Snail (Helicella Alliaria), 

 shell nearly or quite transparent ; the Crystalline 

 Snail (Helicella crystallina), a minute species inhabit- 

 ing a transparent shell with a high polish ; and the 



