90 THE LAND AND FRESHWATER MOLLT78CA OF DORSETSHIRE. 



to eight, very compact, visible in the umbilicus, which is deep; 

 inner lip thin, not continuous with the outer lip, which is not 

 reflected, the border onlv slightly projecting beyond the lower. 

 L. 0.075. B. 0.175. 



Hab. On water-plants in lakes, ponds, and ditches. 

 Watercourses, Chamberlayne's, Bere Regis ; Stoborough 

 Meadows, Wareham ; Sturminster Marshall (J.C.M.P.). 

 Gems ILPHYSA, Lamarck. 



Physa forms a small and natural group with Planorlis and 

 Limncea, to which it is a connecting link, resembling Planorbit, 

 by its long tentacles, and the position of the orifices on the left 

 side, and Limncea, by the form of the shell ; but differing from 

 both in the spire being sinistral. 



1. PHYSA HYPNORUM, Linn., pi. 6. 



BITLLA HYPNORUM, Pult. cat., Rack, ed., p. 43, pi. 18, f. 20. 

 Robinson's Isle of Purleck, p. 178. 



Shell spindle-shaped, bluntly pointed at||the apex, thin, semi- 

 transparent, glossy and polished, yellowish or reddish horn-colour, 

 with very fine longitudinal striae, which are scarcely perceptible 

 even with a magnifying glass ; whorls six to seven, slightly convex, 

 the last surpassing the rest by half the total hoight of the whole 

 shell ; suture well marked and moderately deep ; umbilicus 

 covered ; outer lip thin ; inner lip spread upon the columella. L. 0.5. 

 B. 0.2. 



Hab. Ponds, ditches, upon aquatic plants and grass, in 

 splashy places which are dried up in summer. Newton 

 meadows, near Swanage ; quarry, Wilkeswood farm (Smith); 

 meadows Chamberlayne's, Bere Regis ; banks of river Frome, 

 Dorchester (J.C.M.P ). 



2. P. FONTINALIS, Linn., pi. 6. 



BULLA FOKTINALIS, Pult. cat., p. 40., Rack, cat., p. 43, pi. 21, 

 f. 6. Mont. Test. Brit., vol. 1, p. 226. 



Shell oval, inflated, glossy, transparent, with longitudinal striae, 

 which are scarcely visible even with the aid of a magnifying glass, 

 extremely thin and fragile, greyish horn-colour; whorls four or 

 five, swollen, the last forming three-quarters of the length of the 

 whole shell ; spire very short, blunt ; suture moderately deep ; 

 outer lip very thin ; inner lip widely spread over the base of the 

 penultimate whorl. L. 0.35. B. 0.25. 



