244 HELICID^. 



B. ^^pire short and blunt : mouth horseshoe-shaped, rather 

 oblique, furnished with one or more teeth or folds, and 

 in the young with transverse plates and spiral serewlike 

 ridges : outer lip thickened and reflected. 



2. P. rin'gens *, Jeffreys. 



p. ringens, Jeffr. in Linn. Trans, xvi. p. 356. P. Anglica, F. & H. iv. p. 99, 

 pi. cxxix. f. 6. 



Body yellowish-grey or slate-colour, with several dark 

 lines or streaks along the sides, leaving a clear space in the 

 middle, underneath milk-white: mantle thick, projecting a 

 little beyond the mouth of the shell: tentacles short, of a 

 lighter shade than the upper part of the body; larger pair 

 cylindrical and stumpy, rather close together, the bulbs scarcely 

 distinguishable ; lower pair more like tubercles : foot rounded 

 in front and obtusely pointed behind. 



Shell subcylindiical, inclined to oval, rather solid, nearly 

 opaque, glossy and shghtly iridescent, Hght-brown or yellow- 

 ish-horncolour, closely but slightly striate transversely : peri- 

 pherij rounded, but compressed : epidermis thin : ivkorls 6 or 

 6|, convex, the last being equal to more than one-third of the 

 shell and having its base sharply twisted upwards to form the 

 mouth, the two or three top whorls much smaller in propor- 

 tion to the rest : sjnre short, abruptly and bluntly pointed : 

 suture well defined, but not deep : mouth triangular, rounded 

 below, much contracted by the teeth or folds, which are as 

 follows — two on the pillar (the outside one being larger than 

 the other and extending far into the interior of the mouth in 

 the form of a spiral screw), two on the pillar lip (the outer- 

 most being much the larger and more prominent), and one 

 fold, with from one to three smaller denticles, inside the outer 

 lip and rather deeply seated, the larger one being visible out- 

 side ; besides these, there is a short curved side process or 

 fold, which connects the lip at its outer base with the larger 

 and more prominent tooth on the pillar, so as to resemble one 

 of the lower fronds of a trefoil leaf ; the mouth in unformed or 

 immature specimens is furnished not only with two main spiral 

 ridges (\iz. one on the pillar and the other on the pillar lip), 

 but also with a transverse plate, like those in Planorhis lineatus, 

 which lies at a right angle to the position of the folds within 



* Grinning. 



