CLAUSILIA. 91 



where a narrow but deep channel is formed ; teeth as in C. 

 Holphii ; umbilicus broader than usual in the genus ; clau- 

 silium almost oval, slightly curved, attenuated below. 



This is one of our very local shells. It is found at 

 the roots and on the bark of willows by the Thames at 

 Hammersmith not uncommonly ; and also in Wilts. 



It is much larger than C. Rolphii, and more slender 

 in proportion. It is, moreover, streaked with white. 



4. C. LAMINATA (having plates). 



Similar in shape to the last species, pale reddish horn- 

 colour ; smooth and glossy ; microscopically striated in the 

 line of growth ; nearly transparent ; whorls twelve ; mouth 

 ovate ; teeth very well marked on the columella ; there are 

 also three or four internal laminae which are visible through 

 the transparent shell ; umbilicus small ; clausilium shaped 

 like a shoehorn, but oblong. 



This handsome species is sparingly distributed 

 throughout Great Britain as far north as North- 

 umberland, and is also found in Ireland, but is local. 

 It frequents the beech and ash, at the roots and on the 

 trunks of which it may be found. It occurs in great 

 abundance on the limestone rocks in Derbyshire. 



Yar. I. pellucida. Thinner, more transparent, highly 

 glossy. 



Var. II. albida. Greenish white. 



