148 LIMNiEADiE. 



rent on tlie smaller turns. Whorls five, deeply divltled, 

 rounded, neither angulated nor planulate on either side, of 

 moderately fast increase. Upper disk much and abruptly 

 sunken in the middle ; lower disk flattish. Body about 

 equally broad above and below, not peculiarly contracted 

 towards the mouth ; its lower shelve rather the more 

 slanting ; its periphery neither keeled nor obtuse, but well 

 rounded. Mouth rather large, filling about a third of the 

 breadth, of a rounded lunate figure, not particularly ob- 

 lique, quite as high as broad, much receding below, often 

 stained with purplish smoke-colour, very slightly beyond 

 the level of either disk. Outer lip neither expanded, 

 thickened, nor strictured behind, its junction with the 

 pillar arched, not angular. Breadth an inch ; height, four 

 lines and a half. 



Young shells are conspicuously spirally striated, and in 

 that state have been regarded as a distinct species. 



The animal is nearly black, with a tinge of brown. Its 

 tentacles are bluish-black. When irritated it gives out a 

 purple fluid. 



This fine species is abundant in canals, ponds, ditches, 

 and slow-running streams in the south-east, east, and 

 middle of England, but becomes rare and disappears before 

 reaching Scotland. Its northernmost recorded locality is 

 Dai'lington (Alder.) It is absent from Cornwall and 

 Devon, and is not found in the Isle of Man. Mr. E. J. 

 Lowe has remarked that it attains a peculiarly large size 

 in a dirty ditch at Nottingham, into which a constant 

 supply of warm water runs. Weston-super-Mare (T. 

 Hincks). In Ireland it was first noticed near Maynooth, 

 in Kildare, by Captain Brown. It occurs also about Naas 

 (R. Ball) ; and in Queen's County (Rev. B. J. Clark). A 

 white varictv occurs in the neighbourhood of London. 



