30 



It is a common species, found as far north as 

 Aberdeenshire. 



Var. Draparnaldi. Strise in line of growth stronger. 



5. P. GLABER (smooth). 



Convex above, with a depression in the centre ; concave 

 underneath, rather thin, glossy, horn-colour, finely striated 

 transversely, and still more faintly spirally; whorls five; 

 suture very deep ; mouth nearly circular ; umbilicus large. 



This is a very local shell, being only found in a few 

 places in England, among which are Northumber- 

 land, Durham, Somerset, Norwich, and Birmingham. 

 It resembles P. albus in shape, but is smooth and 

 glossy. It is more liable, perhaps, to be taken for the 

 young of P. complanatus, as the young of that species 

 is only very faintly keeled. 



6. P. SPIRORBIS (circular coil). 



Very flat, rather solid, glossy, brown horn-colour ; whorls 

 five to six ; faintly carinated on the lower margin. 



This is a common shell throughout the British Isles. 

 It is abundant on pond vegetation, and is often found 

 eroded by infusoria, or with a black coating of mud, 

 which is very hard to remove. 



Var. ecarinata. Smaller, grey, no keel, only four 

 whorls. 



