114 CLASS III. GASTEROPODA. ORDER VI. PULMOBRANCHIATA. 
PL CXC. Figs: 
PLanorsis cariNAtus, Miller, Verm., p. 157. Draparnaud, Hist. Moll. 
Fluv. et Terr., pl. 2. f.13 and 14. Encyclopédie Méthodique, pl. 460. 
ii, Pas le (i 
Helix planorbis, Linnzus. 
Planorbis acutus, Poiret. 
Pl. CXC. Fig. 4. 
PLANORBIS BICARINATUS, Sowerby, Genera of Shells, No. 4. 
Pl. CXC. Fig. 5. (fossil.) 
PLANoRBIS EUOMPHALUS, Sowerby, Mineral Conchology, pl. 140. f. 7; 
Genera of Shells, No.4. Deshayes, edition of Lamarck, vol. viii. 
p. 397. 
LYMNAA, Lamarck. 
Testa oblonga vel ovata, interdum turriculata, sepé sinistrorsa, extis 
epidermide plerumque induta, nonnunquam polita; spira exserta, 
prominente, acuta; columella tortuosa, uniplicata ; apertura ampla, 
longitudinali, superné angustaté, marginibus disjunctis, labro sim- 
plici, tenuissimo, acuto. 
In this genus we propose to include the Physe and Lymnee of La- 
marck, as well as the Aplexi and Amphipeplee of Fleming. ‘They were 
arranged by Linneus with the Helices, and Bruguiére referred them to 
his genus Bulimus ; Miiller, however, distinguished them by the generic 
title of Buccinwm, a name which Lamarck subsequently changed to Lym- 
nxa, because it had been previously used by Linneus in reference to a 
well-known genus of marine mollusks. 
The genus Physa was one that Draparnaud proposed for certain sinis- 
tral varieties that are uniformly polished in consequence of the mantle 
being partially reflected over the margin of the aperture ; this separation, 
