THE LAND AND FRESHWATER MOLLUSCA OF DORSETSHIRE. 121 



Genus VIII. BALI A (Bulea) Prideaux. 



Shell sinistral, turriculate, elongated, many-whorled. resembling 

 a young Clausilia, for which it m$y easily be mistaken ; itapproaches 

 the genus Vertigo in its tooth on the pillar ; umbilicus narrow and 

 oblique. 



BALIA PERVERSA, Linn., pi. 10. 



TURBO PERVERSUS, Pult. cat., Rack, ed., p. 51, pi. 19, f. 11. 



Body comparatively large, slender and tapering behind, dark 

 brown passing into a slaty-grey, coverel with small white tubercles 

 and specks. 



Shell spindle-shaped, very thin, fragile, and glossy, yellowish-brown, 

 with indistinct, fine, closelv-set longitudinal striae, and a few 

 transverse ones ; -whorls seven to eitrht, convex, the last inflated ; 

 spire bluntly pointed; suture deep; mouth oval, one whitish 

 tubercular tooth often on theciilumella; outer lip interrupted, thin, 

 slightly reflexed, white ; umbilicus oblique and narrow. L.0.275. 

 B.O.I. 



Hab. On the trunks of trees, ash, sycamore, &c., between 

 the rugosities of the bark, lichen, rocks and walls covered with 

 vegetation. On walls, East Lulworth (Kendall), Smedmore -, 

 Clenston Wood (J.C.M.P. ). 



Genus IX. CLAUSILIA, Draparnaud. 



Shell sinistral, spindle-shaped ; spire long; mouth small with a deep 

 sinus at the upper part, which makes it more or less pyriform, it is 

 also furnished with two spiral plates placed either near the margin, 

 or farther in, where there is also an elastic plate, and moveable, 

 taking the place of an opetcalum; outer lip uninterrupted; umbilicus 

 merely a slit. 



1. CLAUSILIA RUGOSA, Dmpamaud, pi. 10. 



TURBO PERVERSUS, Pult. cat., p. 46 (in part). 



TURBO NIGRICANS, Pult. cat., Rack, ed., p. 51, pi. 19, f. 10. 



CLAUSILIA NIGRICANS, F. and H. iv., p. 121, pi. cxxix., f. 1,2. 



Body small compared with the size of the shell, dark-grey or slate- 

 colour, paler on the sides and underneath. 



Shell club-shaped, solid and not transparent, rather glossy, dark 

 horn-colour, with a few unequal longitudinal whitish streaks, inter- 

 rupted by the sutures; -whorls twelve to thirteen, compressed- 

 suture shillosv ; spire 'liminishmg to a blunt p >int ; mouth oval-pear- 

 shaped, compressed on the outer side; the upp^r tooth or fold 

 proiiinent, and oblique ; thu louver one also ooUque, smaller and 



