72 LAND AND FRESH-WATER SHELLS. 



what resembles Z. palustris. Length \ inch. Marshes, ditches, 

 pools, and muddy streams. Common. Z. truncatula. 



(g) Shell tapering, an elongated cone, thin, glossy, horn- 

 coloured or brownish; whorls seven to eight; mouth elongate, 

 ovate, not above Jrd the length of the shell, provided with a white 

 internal rib ; umbilical cleft very minute. Length i inch. Ponds 

 and ditches. Local. Z. glabra? 1 



12. Ancylus. Shell conical, oblong, limpet-shaped; apex 

 pointed and bent to the right; spire dextral. Animal with two 

 cylindrical tentacles, with the eyes at their base; foot large. 



(a) Shell conoid, thin, yellowish-grey or horn-coloured ; apex 

 recurved ; mouth ovate. Height to ^th inch. Streams and 

 rivulets. Common as far north as Aberdeen. A.fluviatilis?* 



13. Velletia. Like Ancylus ', but with the apex of the shell 

 bent towards the left; spire sinistral. 



(a) Shell oblong, horn-colour tinged with yellow or green, thin, 

 glossy, compressed at the sides ; apex acute, sub-central , mouth 

 somewhat oblong. Length |th inch. Lakes, ponds, canals, and 

 sluggish streams. Somewhat local. K lacustris 



(TERRESTRIAL.) 

 Family II. Limacidse. 



Shell placed under the mantle, granular or shield-like. Body 

 united in its whole length with the foot beneath, there being 

 no visceral hump ; tentacles four, cylindrical, the dorsal pair 

 bearing the eyes ; mantle shield*like. 



36 v. albida, smaller, milk-white ; v. major, larger, ashy, more tumid ; v. 

 Dentricosa, more bellied, spire short, peristome without swelling ; v. minor, 

 smaller, horn-coloured ; v. elegans, much larger, more solid, more slender, 

 greyish-white, marked with coarse spiral ridges, spire more produced, suture 

 oblique, outer lip thickened. 



37 v. major, much larger ; v. elongata, more produced, so as to alter the 

 relative proportions of length and breadth; m. decollatum, spire decollated. 



38 v. capuloides, elevated, very convex anteriorly and laterally, nearly convex 

 behind, aperture oboval ; v. albida, milk-white, striae finer ; v. gibbosa, slightly 

 elevated, extremely convex, subgibbous in front, convex laterally, nearly straight 

 posteriorly, apex obtuse, aperture oboval ; v. costata, whitish or greyish, stria 

 well marked. 



39 v. albida, milk-white ; v. compressa, rather larger and considerably broader 

 and flatter. 



