146 LIMNiEADiE. 



P. ACUTA, Draparnaud. 



Physa ar„la, Drap. Moll. Ter. et Fluv. France, p. 55, pi. 3, f. 10, 1 1.— Brown, 

 111. Conch. G. B. pi. 14, f. 58, 59 (copied from Drap.).— Bkard, 

 Coq. Envir. Paris, p. C9, pi. 7, f. 5, 6. — Michaud, Comp. Drap. 

 Moll. France, pi. 16, f. 19, 20.— D'Orbig. Moll. Canar. p. 74. 

 — Desh. Lam. Anim. s. Vert. (ed. Desh.) vol. viii. p. 403. — 

 Mermet, Moll. Pyren. p. 70. 

 „ subopaca. Lam. Anim. s. Vert. (ed. Desh.) vol. viii. p. 401 (teste Michaud). 



A sout?iern Continental species, figured hy Brown for the P. 

 fontinalis, var. acuta, 



P. ALBA, Turton. 



Physa alba, Turt. Zool. Journ. 1825, vol. ii. p. 363, pi. 13, f. 3; Manual Land 



and F. W. Shells, p. 128, f. 1 1. — Jeffreys, Trans. Linn. Soc. 



vol. xvi. p. 521.) 



„ am/oria, Michaid, Bull. Linn. Soc. Bordeaux, 1829, vol. iii. p. 368 (from 



which Esp. Nouv. Coq. 1829, p. 9, pi. 1, f. 15, IG; Comp. 



Drap. Moll. France, p. 83, pi. 16, f. 21, 22). 



Diaatroplia „ Gray, Manual Land and F. W. Shells, p. 16, f. 11 1, as spurious 



(no description). 

 Physa fontinalis. Brown, 111. Conch. G. B. p. 30, pi. 14, f. 56, 57. 



A native of Southern Utirope and Northern Africa, mtroduced 

 hy Turton as from the river Torvin, in Wales. 



PLANORBIS. Muller. 



Shell spiral, discoid, dextral, of many whorls ; aperture 

 elliptical or semi-lunar, margin entire. 



Animal with a stout, broad, proboscidiform head, flanked 

 by two setaceous, or subulate tentacula, with eyes at their 

 inner bases. Foot short, obtuse behind. Tongue with 

 transverse rows of numerous quadrate uncinated teeth. 



This very patural genus, representatives of which dif- 

 fering but slightly from species still living, are found in 

 fresh-water strata of even the oolitic epoch, has preserved 

 its form with great constancy, nor do the members 



