HELIX. 37 



the outer one of which is very sharply carinated at the 

 circumference, the purplish rufous colour, and its 

 unpolished surface. Animal a dusky green colour, 

 with two dark streaks running down the back. 



Hah. A widely-distributed species, though of ne- 

 cessity local owing to its habits. This is a shell not 

 only peculiar to limestone districts, but to the rocks 

 themselves, in the fissures of which it secretes itself 

 during the drought of summer, and it is only after a 

 period of settled wet weather that it can be found 

 abundantly, even in localities where it is known to 

 be numerous. We can well remember, when taking 

 an excursion in Wensleydale, being very much disap- 

 pointed at not finding them on the limestone rocks, 

 with the exception of one or two specimens, though 

 we knew they abounded there, a number having been 

 sent us from the same locality, together with the infor- 

 mation that they actually swarmed upon the rocks and 

 walls during the wet weather. It has been found on 

 limestone rocks, in Wensleydale, the south of Durham, 

 the south of Yorkshire, and on chalky rocks in the 

 south-east of England. 



H. RUFESCENS. Pennant. PI. VI, fig. 19. 



Shell depressed, reddish horn colour, concentrically striated, slightly 

 carinated and white at the circumference ; umbilicus large. 



This shell is generally diffused over England, prefer- 

 ing a chalky soil, where they grow to great perfection. 

 Those found in the north of England are more globular 

 and smaller, seldom being half an inch in diameter, 

 while the typical form, sometimes measures nearly 

 three quarters of an inch. Though the shell varies in 

 colour, it cannot well be confounded with any other 

 species. 



Hah. Found in almost every district. Its favourite 

 place of resort, where there are no calcareous rocks, is 

 at the foot of a wall, where they no doubt derive some 

 of their necessary support. More common in the 

 south than the north of England. 



