CLAUSILIA. 91 
where a narrow but deep channel is formed ; teeth as in C. 
Rolphit ; wmbilicus 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. Rolphit, 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 lamine which are visible through 
the transparent shell; wmbilicus 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. 
Var. I. pellucida. Thinner, more transparent, highly 
glossy. 
Var. II. albtda. Greenish white. 
