PUPA. 77 



traneous matter is not suitable for attachment (as in 

 the calcareous districts of Derbyshire), the shell is 

 found clean and smooth in the crevices of rocks. 

 Though often met with in hedge-banks among damp 

 moss and earth, it never occurs in any quantities. 

 Var. alba. White or colourless. 



Genus VI. PtfpA. 



1. P. SECALE (a grain of rye). 



Globosely conical, solid, opaque, rufous brown ; regularly 

 striate in the line of growth ; whorls eight to nine ; mouth 

 horseshoe- shaped, furnished with eight or nine white 

 ridges having the appearance of teeth. 



There is no mistaking this species. It is far the 

 largest of our Pupa. Though local, it is abundant 

 where it occurs on rocks, in woods, chiefly in cal- 

 careous districts in England and South Wales, but 

 not in Ireland or Scotland. 



Var. I. alba. White. 



Var. II. Boileausiana. "It is distinguished from 

 the type by its smaller size, the larger plication being 

 always double, and by the presence of a prominent 

 additional fold at the angle of the columella." 



Var. III. edentula. Smaller and thinner, smooth 

 and glossy, tooth-like processes absent 



