PIIYSA. 143 



spire. The penult whorl appears peculiarly developed, 

 the apex is decidedly blunt, the aperture fills at times but 

 five-eighths of the total length, and the pillar is short and 

 twisted. The original individuals were obtained from 

 Anglesea, in 1833, but afterwards bred in a water-butt, 

 which unusual habitat may have changed the aspect of 

 their progeny. 



The animal is of a pale yellowish grey, darkening in in- 

 dividuals to a deep fuscous hue. Its tentacles are long 

 and slender, with conspicuous black eyes at their inner 

 basis. The mantle is highly contractile, and when ex- 

 panded envelopes a great part of the shell, and is divided 

 at the edge into finger-like processes. It is bilobed, the 

 columellar division having more digitations (usually five), 

 than that which is projected over the spire. The foot is 

 obtusely angled in front and pointed behind. It does not 

 appear that there are any essential differences distin- 

 guishing the animals of the different varieties. They all 

 advance with a jerking motion. 



This pretty mollusk is common in pools, lakes, and 

 ditches throughout the greater part of the British islands, 

 ceasing, probably, only in the extreme north. Both large 

 and small varieties occur in most districts. 



P. HYPNORUM, Linnaeus. 



Oblong-conical : spire pointed, elongated. 



Plate CXXII. fig. 6, 7. 



Iliilla /ii/pitorim, Linn. Syst. Nat.ed. 12, p. 1102. — Mont. Test. Brit. p. 228. 

 — Maton and Rack. Trans. Linn. Soc, vol. viii. p. 127, 

 pi. 4, f. 3. — Rack. Dorset Catalog, p. 43, pi. 18, f. 20. — 

 TuRT. Concli. Diction, p. 488. — Chemn. Conch. Cab. vol. ix. 

 pt. 1, p. 34 (in part), pi. 103, f. 883, n, b. — Dillw. Recent 

 Shells, vol. i. p. 488.— Wood, Index Testae, pi. 18, f. 39. 



