MA1ACOZOA. GASTEROPODA. PULMOBRANCHIATA. 87 



Helix aculeata. Muller, Verm. Terr, et Fluv. ii. 81. Helix 

 aculeata. Drap. Moll. 82. PI. 7. f. 10, 11. Helix spinulosa 

 Mont. Test. Brit. 549. PL 11. f. 10. Helix aculeata. Gray's 

 Turton, 149. PI. 4 f. 38. 



9. Helix pulchella. Little White Snail. 



Shell depressed, equally convex on both sides, deeply um- 

 bilicate ; the whorls deeply striate transversely ; greenish- 

 white, nearly opaque ; the aperture circular, with the margin 

 thick, flat, and reflexed. Diameter, one-twelfth of an inch. 



The animal white, or yellowish- white. 



The peristome is nearly complete ; the spiral turns trans- 

 versely grooved, often at intervals marked with prominent 

 ridges, being the remains of former reflexed peristome margins. 

 The shell thin, usually semitransparent and greenish-white, 

 sometimes opaque and white. 



Abundant among moss on the inner sand-hills between the 

 Dee and the Don ; under stones in the pasture adjoining the 

 Bay of Nigg; and in various other parts along the coast, as 

 well as far inland. 



Helix pulchella. Muller, Verm. Terrestr. et Aquat, ii. 30. 

 Helix pulchella. Drap. 112. T. 7. f. 30, 31, 32, 33, 34. Helix 

 crenella. Mont Test. Brit. 441. T. 13. f. 3. Helix pulchella. 

 Grey's Turt. 141. Helix costata. Flem. Brit. Anim. 263. 



GENUS 2. ZONITES. ZONE-SNAIL. 



Animal elongated, very slender; with an elongated 

 extremely compressed foot, which extends far behind; 

 four tentacula, the upper long, the lower short, all ter- 

 minating in a knob. In other respects like that of Helix. 



Shell orbicular, depressed, little convex above, widely 

 umbilicate beneath, very delicate, generally transparent 

 and glossy ; the aperture roundish-semilunar, with a very 

 thin margin. 



The last-mentioned character, and the discoid or flat- 

 tened form of the shell, distinguish this genus from 

 Helix. 



When the animal is in motion, the shell is balanced 

 obliquely or nearly horizontally on its back, the umbili- 

 cated surface being lowest. The tentacula are protruded 

 and withdrawn with surprising quickness. The species 



