75 



b. smaller, slenderer, and not so distinctly 

 striate. 



c. with a small denticle or two between the 

 plaits. 



Clausilia rugosa. Drap. p. 73. t. 4./. 19, 20. 



. Leach, Mollusc, p. 121. 



Turbo bidens. Montagu, p. 357. t. II. f. 7. 

 Turbo nigricans. Turt. Diet. 225. Dillw. 375. 



Shell about half an inch long, glossy black or grey, 

 often marked with short cinereous streaks, with 

 regular raised lines which when closely examined 

 appear a little granular : spire composed of from 

 seven to ten rather raised volutions : aperture 

 oval, with the inner lip a little contracted with 

 three plaits all on the pillar, the lower one interior 

 and hardly distinguishable in the full-grown shell ; 

 the margin thick and white, but not reflected, de- 

 tached all round. 



Common under stones and in old walls. 



59. CLAUSILIA. parvula. Shell very slender, brown, 

 quite smooth : aperture with two plaits ; the mar- 

 gin thick, white, slightly reflected, detached all 

 round. 



