BALEA. 115 



Clatisilia perversa, Charpent. N. Denks- Schweiz. Ges. Nat. 1837, p. 17. 



Fusidus fragilis, Fitzing. Vers. Ostreich Weichth. p. 105. 



lialcea perversa, Gray, Manual L. and F. W. Shells, p. 207, pi. G, f. 70. — 



Thompson, Ann. Nat. Hist. vol. vi. p. 115. 

 ClausiUa uniplicata, Calcara, Effem. Sc. et Let. Sicil. p. 82. 

 Stomodonta fragilis, Merm. Moll. Pyren. p. 48. 



Shell small, sinistral, very thin, fusiform-turreted, of 

 a semi-transparent olivaceous or yellowish horn- colour, 

 with a satin-like lustre, slightly roughened by delicate 

 somewhat irregular, and partially obsolete longitudinal 

 raised wrinkles. Whorls from six to nine, moderately 

 convex, strongly defined ; the last rounded at the base ; 

 spire turreted ; apex rather acute for the genus. Aperture 

 from angulated pyriform to rounded pear-shaped; outer 

 lip a little arcuated. Peristome thin, simple, slightly 

 reflected upon the columella, where it is white, and forms 

 an incipient subumbilicus ; margins united in the aged 

 shell by a thin callus, from whence issues a small parietal 

 lamella ; no other folds ; left lip sinuous above. 



A third of an inch is about the ordinary length of 

 specimens, although some are occasionally obtained five 

 lines long. 



The animal of this shell reminds us more of the aspect of 

 a BuKmus (especially of B. acutus) than of a Pupa or 

 ClausiUa. It is dusky grey above, striped with a mottled 

 dark band on each side of the neck ; these bands become 

 very dark on the rather stout and long clavate upper 

 tentacula, and send branches down to the very short lower 

 tentacula. The foot, sides and tail are very pale grey. 

 When crawling it carries the shell in a line straight away 

 behind it. 



This shell is widely, if not quite generally distributed 

 throughout the British Isles. It delights more especially 

 in living upon trees, and may be found in numbers often 



