40 LIMNJLID.^. 



5. P. gla'ber,* Jeffreys. Pl. IV. 



" Body yellowish-grey ; tentacles rather short, cylindrical and 

 ending in a blunt point ; foot rather broad, especially in front, 

 with a yellowish edge." — B.C.^ vol. i. p. 85. 



Shell somewhat convex above with a depression in the centre, 

 concave underneath, rather thin, glossy, greyish horn-colour, 

 sometimes marked transversely with curved streaks of a whitish 

 colour, with fine irregular stride in the line of growth, and micro- 

 scopically striate spirally ; epidermis thin ; periphery rounded, 

 not keeled ; whorls 5, convex but slightly angulated, body whorl 

 occupying about one-half of the shell ; suture strongly defined ; 

 7nouth nearly circular ; outer lip slightly reflected ; ijiner lip 

 joined to the base of the penultimate whorl, continuous with the 

 outer lip ; umbilicus large. 



This species was first described by Gwyn Jeffreys, 

 in the 'Transactions' of the Linnean Society 

 (vol. xvi. p. 387). Though its range in this country 

 is a wide one, extending from the Shetland Isles 

 to Land's End, it is extremely local, but abun- 

 dant where it occurs. It has been observed in the 

 following localities, and will probably be found, from 

 time to time, in other places. Near Norwich (Bridg- 

 man), B.C. Ackworth Park, Yorkshire (C. Ashford), 

 Northumberland and Durham (W. D. Sutton), near 

 Birmingham (G. Sherriff Tye), J.C. Somersetshire 

 (Norman). 



The chief points of difference between this shell and 

 that of P. albus consist in its being smaller, and glossy 

 instead of dull, in the convexity of the upper surface, 

 and more particularly in the absence of the strong 

 spiral striae which are so characteristic of the latter. 



Var. compressa. — Shell more concave below than in the type, 

 and only depressed in the centre on the upper side, the whorls 



* Smooth. 



