9O LAND AND FRESH-WATER SHELLS. 



sometimes with a denticle at the base of the penultimate whorl ; 

 peristome thin, umbilicus narrow. 



(a) Shell fusiform, turreted, glossy, yellowish horn-colour 

 streaked with white ; whorls seven to eight ; suture deepish ; 

 mouth rounded, pear-shaped, with sometimes a denticle near the 

 middle of the base of the penultimate whorl ; umbilicus small. 

 Height 2%ths inch. Under the bark of old trees. Local. 



B. perversa. m 



23. Clausilia. Shell sinistral, fusiform ; mouth pyriform or 

 elliptical, toothed, furnished with a clausilium ; umbilicus very 

 small. 



(a) Shell cylindrical, glossy, chocolate-brown or horn-coloured, 

 marked with whitish streaks ; whorls ten to thirteen ; mouth pyri- 

 form, furnished with two plications on the base of the penultimate 

 whorl with one to three smaller plaits between them, and with 

 two plications on the columella ; umbilicus narrow ; clausilium 

 oblong. Height f ths inch. Under stones, logs of wood, and 

 among grass on hedge-banks, on trunks of beech, willow, and ash 

 trees. Common. C. rugosa.^ 



(b) Shell fusiform, reddish or yellowish-brown ; whorls nine to 

 ten, swollen ; mouth rounded, pyriform, with plaits as in C. rugosa, 

 but the lower one on the base of the penultimate whorl is less 

 prominent and sometimes cruciate j umbilicus indistinct ; clausilium 

 oblong. Length -|fths inch. Among dead leaves and under 

 the bark of tress. Rare. C. Rolphii. 



(c) Shell fusiform, yellowish-brown, streaked with white ; whorls 

 twelve to thirteen, compressed ; mouth pear-shaped, canaliculated, 

 with the same plaits as in the two foregoing species, except that 

 the teeth between the plications on the base of the penultimate 

 whorl are not represented ; umbilicus rather broad, basal crest 

 prominent , clausilium oval. Length |~Jths inch. On the bark 

 of willow trees. Very local. C. biplicata. 



88 v. viridula,) greenish-white, transparent. 



89 v. dtibia, larger, more ventricose ; v. gradlior, longer, more slender ; v. 

 tumidula, smaller, shorter, more ventricose ; v. Everetti, shorter, whorls 

 fewer ; v. Schlechtii, like v. dubia but larger, elongated, smoother, and more 

 transparent, pale brown. (Possibly v. dubia is a distinct and separate 

 species.) 



