150 LIMN^AD^E. 



from the greater prominence of one of the spiral lines. 

 Mouth oboval-lunate, peculiarly receding below, rather 

 large, filling more than a third of the breadth, quite as 

 broad as high, not peaked below, where it projects slightly 

 beyond the level, slightly beneath the level above. Outer 

 lip acute, a little disposed to expand, curving to the pillar 

 without angularity. Diameter a quarter to a fifth of an 

 inch. 



The animal is variable in colouring. Individuals which 

 we have taken near London, are of a pale ashy grey, with 

 black head and neck, and very pale tentacles ; those we 

 have gathered in ditches among the peat bogs in the Isle 

 of Man are of a general reddish-yellow colour, darkening 

 to red on the neck and head, and shining red through the 

 body whorls ; and Mr. Spence Bate has communicated a 

 drawing, taken from specimens at Swansea, in which the 

 head, neck, and tentacles of the animal are represented of 

 a brownish white, and the sides of foot and proboscis, of a 

 deeper brown. The colouring of Scottish specimens de- 

 scribed by Mr. Macgillivray, is also somewhat different. 



It lives on water-plants, especially Potamogeton, and is 

 widely distributed through the British Islands ; so ge- 

 nerally, indeed, that any enumeration of localities would 

 be superfluous. 



P. glaber, Jeffreys. 



Small, depressed, not keeled, smooth or nearly so (no spiral 

 sculpture), whorls of rather fast increase, mouth roundish. 



Plate CXXVI. fig. 8, 9. 



rianorbis glaher, Jeffreys, Trans. Linn. Soc. vol. xvi. p. 387, teste Jeffreys. — 



Potiez and Mich. Gal. Douai, Moll. p. 211. 



„ lavis, Alder, Trans. Nat. Hist. Soc. Northumb. vol. ii. p. i'>;S7; Mag. 



Zool. and Bot. vol. ii. p. 1 13. — Gray, Manual L. and F. \V. 



Shells, p. 261, pi. 12. f. 118. — Thompson, Ann. Nat. Hist. 



vol. vi. p. 121. — Hrovvn, Illust. Conch. G. H. p. 31. 



