§4 HELICIDiE. 



C. NIGRICANS. Maton and Rackett. PL VI, fig. 30. 



Shell slender, opaque, dark brown ; five more or less raised, some- 

 what granular, strias ; mouth with three plates, margin white. 



Clausilia rugosa. Brown. 



This is by far the commonest of our British Clausilia, 

 being abundant almost everywhere. It may readily 

 be distinguished from the others by being so much less, 

 seldom attaining half-an-inch in length. It is nearly 

 opaque with a dark brown lustre, often marked with 

 whitish streaks. The spire is composed of from seven to 

 eleven moderately convex volutions. Aperture small 

 and pyriform. 



var. DUBiA, (Plate VI, fig. 31,) is somewhat larger, 

 more ventricose ; the strise broader and more raised. 



Hah. Plentiful in almost every locality in the 

 British Isles. It may be found under stones on walls 

 and rocks (particularly limestone), in the earth or even 

 on trees. The variety occurs in the north-east of 

 England. Tanfield, near Hipon, Haughton-le-spring, 

 near Sunderland, &c. ; it has been found as far south 

 as Oxford. 



ZuA. Leach. 



Shell — Spiral, ratlier cylindrical, hlimt, smooth and jpolished ; 

 mouth ovate ; peristome toothless, thichened hut not 

 rejiexed. 



Animal — Allied to and closely resemhling JBulimus. 



Z. LUBRicA. Muller. PL VI, fig. 32. 



Helix lubrica, Mont. Bulimus lubricus, Breton. 



At first sight there is a considerable likeness between 

 this species and Azeca tridens, but its lighter colour, 

 slender shape, and more prominent whorls will readily 

 distinguish it ; besides the never-failing characteristic, 

 the mouth, which in this shell is almost oval, quite 

 plain, and not furnished v/ith projections as in ^. tridens. 

 This genus is distinguished from Bidimus by its pol- 

 ished periostraca. The shell varies in size and colour, 

 though generally an olivaceous brown; it is highly 



