29 
Acuatina.—Shell oval or oblong: aperture entire, longitudinal; the right lip sharp, 
never reflected. Columella smooth, truncated at the base. 
(1) Shells with the last whorl ventricose, not depressed. 
Plate XV. Fig. 5, A. virginea. (Bulla virginea.—Linn.) 
(2) Shell with the last whorl depressed, or attenuated towards the base. 
Plate XV. Fig. 5 (a). A. albo-lineata. (Voluta leucozonias.—Gmel.) [Mrs. Mawe’s Cabinet.] 
Succinra.—Shell oval or ovate-conical: aperture large, entire, longitudinal; the right 
lip sharp, not reflected, united at the lower part toa smooth, sharp, attenuated 
columella. No operculum. 
Plate XV. Fig 6. S. amphibia. (Helix putris.—Linn.) 
AvurRicuLa.—Shell suboval or ovate-oblong: aperture longitudinal, very entire at the 
base, contracted at the upper part, where the margins are disunited. Columella 
with one or more plaits; the lip or margin sometimes reflected outwards, some- 
times simple and sharp. 
(1) Shells mith the margin reflected outwards. 
Plate XV. Fig. 7. A. Jude. (Voluta auris Jude —Linn.) 
(2) Shells with the margin simple and acute. 
Plate XV. Fig. 8, 8 (a). A. monile. (Voluta flava —Gmel.) 
Cyctostoma.—The shape of the shell variable; whorls of the spire cylindrical: aperture 
round, regular; the margins circularly united, or reflected by age. An oper- 
culum. 
Plate XV. Fig. 9. C. volvulus. (Helix volvulus.—Linn.) [Mrs. Mawe’s Cabinet.] 
LYMNAEANA. —3 GENERA. 
Shell spirivalve, the external surface mostly smooth; the right margin of the aperture always sharp, 
and not reflected. 
Pxianorsis.—Shell discoidal, spire depressed, the whole of the whorls shewn above and 
beneath: aperture oblong, lunate, very distant from the axis of the shell; the 
margin never reflected. No operculum. 
Plate XV. Fig. 10. P. corneus. (Helix cornea.—Linn.) 
Puysa.—Shell convolute, oval or oblong; the spire prominent: aperture longitudinal, 
contracted at the upper part. Columella twisted: right lip very thin, sharp, part- 
ly projecting above the plane of the aperture. No operculum. 
Plate XV. Fig. 11. P. rivalis. (Lymnza rivalis.—Sowerby.) 
Lymn a.—-Shell oblong, sometimes turreted; the spire prominent: aperture entire, lon- 
gitudinal, outer lip sharp; the lower part ascending over the columella, forms a 
very oblique plait, re-entering the aperture. No operculum. 
Plate XV. Fig. 12. L. stagnalis. (Helix stagnalis.—Linn.) 
