FAMILY LYMN/EACEA. 153 



2. Physa hypnorum, Moss Physa. 



Shell ; sinistral, fusifomily oblong, very thin, transparent, brittle, 

 shining, spire attenuately produced, whorls 

 five, convex, faintly irregularly striated in 

 the direction of the lines of growth, opake- 

 ly margined at the sutures ; aperture ob- 

 liquely ovate, rather narrow, columella cal- 

 lously edged. 



Bulla hypnorum, Linnssus (1758), Syst. Nat. 10th 

 edit. p. 727. 



Planorbis turritus, Miiller (1774), Verm. Hist, part ii 

 p. 169. 



Bulla turrita, G-melin (1788), Syst. Nat. p. 3428. 



Helix marmorata, Gmeliu (1788), Syst. Nat. p. 3665. 



Bulimus hypnorum, Bruguiere (1789), JEnc. Meth. Vers, vol. i. p. 301. 



Physa hypnorum, Draparnaud (1801), Tdbl. Moll. p. 52. 



Physa turrita, Studer (1823), Kurz. Verz. p. 92. 



Limnea turrita, Sowerby (1853), Gen. Limn. f. 10. 



Aplexa hypnorum, Fleming (1828), Brit. Anim. p. 276. 



Nauta hypnorum, Leach (1831), Turf. Man. p. 152. 



Physa cornea, Massot (1845), Soc. Agr. Pi/r.-Orient. vol. vi. part 2. p. 236. 

 f.4. 



Physa (Nauta) hypnorum, Moquin-Tandon (1855), Hist. Moll. vol. ii. 

 p. 455. pi. xsiii. f. 11 to 15. 



Hob. Northern and Central Europe to the Pyrenees. Arctic Siberia. 

 Throughout Britain. (In ponds and ditches, upon blades of grass 

 and other plants.) 



This more elongated species is very distinct from the preceding, 

 and it is not without good grounds that it has been regarded as 

 a separate genus, Aplexa. In Physa fontinalis the mantle is re- 

 flected over the shell on either side in a fringed or digitate lobe; 

 in Physa hypnorum it is not reflected beyond the merest lodgment 

 on the edge of the shell; and the shell, notwithstanding, is the 

 more brittle and glossy of the two. Another peculiarity in the 

 species under consideration, consists in the tentacles being more 

 slenderly subulate, whilst the animal is altogether darker in colour. 

 There is, too, an additional whorl in the shell. The mantle of 

 P. hypnorum, according to the observations of M. Desmoulins, is 

 ocellated with yellow or golden spots, like that of P. fontinalis. 



Its range of habitation is rather partial in Britain, and in 

 Europe its place is taken below the Pyrenees by Physa acuta. It 



