WALACOZOA. GASTEROPODA. PULMOBRANCHIATA. 101 



generative organs united, and having their orifice near 

 the riglit tentaculum. 



Shell subcylindrical, spirate, veiy thin, transparent ; 

 with the apex obtuse, the whorls convex, compressed, 

 the last whorl not proportionally larger ; the aperture 

 moderate, with the peristome circular, incomplete, more 

 or less thickened, but not reflexed. 



Vertigo differs veiy little from Pupa, the animal being 

 similar, with the exception of not having the lower ten- 

 tacula developed, and the shell with the peristome thinner. 



1. Vertigo edentida. Toothless Whorl-SnaiL 

 Shell ovato-cylindrical, subconical, moderately glossed, 

 transparent, with five convex turns, which are transversely 

 striated, and distinctly separated by the suture, the second 

 whorl mucli larger than the first, greatly exceeded by the third, 

 which is little less than the fourth, the fifth not m\ich larger ; 

 the aperture semiovate, toothless, with the peristome slightly 

 thickened, incomplete ; the umbilicus narrow ; the colom- dark 

 olive, the peristome paler. Length three-fourths of a twelfth, 

 breadth rather more than half the length. 



A single specimen foimd by me, on the 25th of June, 1842, 

 when witli my class on an excursion, beneath a fragment of 

 serpentine, on a hill of that rock, at Potterton, Parish of Bel- 

 helvie, six miles from Aberdeen. Another found by Mr. 

 Leslie, in September, near Inverury; and one by Miss Mac- 

 gillivray in the Den of Auchmedden. 



Pupa edentula. Drap. Moll. Terr. et. Flu v. 59. PI. 3. f. 28, 29* 

 — Pupa edentula. Flem. Brit. Anim. 269. — Vertigo edentula. 

 Alder, Mag. Zool. and Bot. ii. 1 12. 



Genus 9. Clausilia. 



Animal with the body elongated, spiral; the head 

 with four tentacula, of which the upper are short or 

 moderate, filiform, the lower very short, all capitate ; 

 the foot small, compressed, oblongo-lanccolate. 



Shell slender, tnrrite, subfusiform, thin, with the spire 

 tapering to an obtuse point ; the whorls numerous, the 

 last smaller than the next ; the aperture generally re- 

 versed, suboval, oblique, with the peristome continuous, 

 free, marginate, and toothed or plicate ; the throat with 



