29 
Aciiatina. — 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.] 
Succinea. — Shell oval or ovate-conical: aperture large, entire, longitudinal; the right 
lip sharp, not reflected, united at the lower part to a smooth, sharp, attenuated 
columella. No operculum. 
Plate XV. Fig 6. S. amphibia. (Helix putris. — Linn.) 
Auricula. — 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 with the margin reflected outwards. 
Plate XV. Fig. 7- A. Judse. (Voluta auris Judae — Linn.) 
(2) Shells with the margin simple and acute. 
Plate XV. Fig. 8, 8 (a). A. monile. (Voluta flava. — Gmel.) 
Cyclostoma. — 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.] 
LYMNALANA — 3 Genera. 
Shell spirivalve, the external surface mostly smooth; the right margin of the aperture always sharp, 
and not reflected. 
Planorbis. — 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.) 
Piiysa. — 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. (Lymnaea rivalis.— Sowerby.) 
Lymnasa. — 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.) 
