CLAUSILIA. 123 



convex, crowded with fine longitudinal raised striae, which 

 assume a somewhat granulated appearance under the lens, 

 from being closely decussated by almost obsolete spiral 

 lines ; last whorl much contracted near its base, and some- 

 what scrobiculated by the hollows on either side of the 

 rather prominent basal fold ; spire perceptibly attenuated ; 

 apex but little obtuse. Aperture small, pyriform, rather 

 elongated than otherwise, occasionally subcanaliculated at 

 the base ; peristome of a whitish or pale brownish hue, 

 rather strong, elevated, continuous, not broadly reflected. 

 Upper lamina of the pillar-lip, acute, prominent, and near 

 the outer lip ; lower lamina more deeply seated, bifur- 

 cated ; an occasional intermediate minute fold. A distinct 

 lunella or basal fold, a sunken subcolumellar one, a narrow 

 superior palatal one, and sometimes a second running trans- 

 versely from the palatal callus. Scarcely half an inch 

 long. 



Variety duhia (f. 2). Larger, more ventricose anteriorly, 

 brownish ; the lunella and subcolumellar fold more or less 

 obsolete. 



The animal is rather elongated for its genus, the foot 

 being narrower than in allied forms. It is dark grey, rather 

 mottled and rugose above, paler about the foot and tail. 

 The upper tentacles are stout and clavate, the lower ones 

 very short. 



This is a universally diffused British and Irish shell, 

 living under stones, on walls, and occasionally in crevices 

 of trees. On chalk downs the smaller variety is common. 

 The large form, dubia, is well known in the north-east of 

 England. Like many other widely distributed land-shells, 

 it is subject to great variation, and has been split up by 

 Continental authors into several spurious species. 



