HELICIDJE. *217 



Mr. Alder, who first introduced this shell into 

 the Fauna, observes, that it is undoubtedly the 

 C. dubia of continental authors. It may be distin- 

 guished from C. rugosa by its greater size and ventri- 

 cosity. 



82. 5. CLAUSILIA nigricans. Dark Close Shell, 

 (t. 5. f. 58.) Shell slender, sub-opake, black- 

 brown, with fine raised somewhat granular 

 striae; aperture with three plaits, the margin 

 white and detached all round. 



Helix perversa. Miiller, Verm. 118. 



Bulimus perversus. Brug. 



Clausilia rugosa. Drap. p. 73. t. 4. f. 19, 20.; 

 Leach, Mollusc, p. 121. 



Turbo bidens. Montagu, p. 357. t. 11. f. 7. 



- nigricans. Dillw. 375. ; Pult. Dorset. 46. ; 

 Turt. Diet. 225. 



Turbo perversus. Perm. Brit. Zool. iv. t. 82. f. 116. 



Clausilia nigricans. Jeffreys, Linn. Trans. xvi 

 351. 



Odostomia nigricans. Flem. Ed. Ency. 



Clausilia perversa. Flem. 



Var. I. smaller, more slender. 



Clausilia parvula. Leach, MSS. B. M. ; Turf on, 

 Zool Journ. ii. 556., Man. ed. 1. 74. f. 58. ; 

 Jeffreys, Linn. Trans, xvi. 352. ; not Studer. 



Var. 2. shorter, fewer whorls. 



Clausilia Everettii. Miller, Ann. Phil. n. s. xix. 

 377. 



Common under stones and in old walls. 

 Animal brown, corrugated, foot narrow. 

 L 



