44 LIMNJEID^. 



Var. disciformis. — " Shell flatter and thinner, of a yellowish 

 colour, having the last whorl larger in proportion to the others, 

 and the keel more prominent and sharp, and placed exactly 

 in the middle. It is found in Bucks, Oxford, Cambridge, 

 Glamorgan, Cork, and Tipperary, and is somewhat rare.'' — B.C.,, 

 vol. i. p. 90. Titterford and Sutton-Coldfield near Birmingham 

 (G. SherriffTye), y.C 



9. P. COMPLANA'TUS,* LiNNfi. Pl. IV 



Body dark violet-red, very slightly transparent ; tentacles fili- 

 form, slender, somewhat pointed at the tips, thicker at their 

 base, yellowish faintly tinged with rose-colour; eyes small, 

 round, black; foot violet-red, greyish at the edges, finely 

 spotted with black, rounded in front, and ending in a blunt 

 tail. 



Shell concave above, nearly flat beneath, thickish, almost 

 opaque, usually of a dullish appearance, brownish or greyish 

 horn-colour, with close-set striae in the line of growth, and 

 indistinctly striate spirally ; epidermis thickish ; periphery 

 strongly keeled below ; whorls 5-6, rapidly enlarging, more 

 rounded than in P. carinatus, body whorl in breadth about one- 

 quarter of the shell ; suture deepish ; mouth rounded-oval, some- 

 what angulated above, often ribbed internally; outer lip slightly 

 reflected ; i7iner lip spread over the base of the penultimate 

 whorl and continuous with the outer lip ; umbilicus large but 

 not deep. 



Inhabits slow rivers, ponds, and stagnant water in 

 most places in England, Wales, and Ireland. In 

 Scotland it is abundant near Edinburgh, in Dud- 

 dington and Lochend Lochs, as well as in marshes at 

 Lufifness Links, East Lothian (McMurtrie). 



Like the preceding species, this is a sluggish and 

 irritable creature ; when touched it instantly falls from 

 the object to which it had attached itself, retreating 



Flattened. 



