Planorbis. mollusca. pulmonifera. m 
118. A. rivalis. — Spire short, pointed ; aperture contracted 
anteally. 
Bulla riv. Maton and RacJcett^ Linn. Trans, viii. 126. tab. iv. f. 2. Turt'> 
Conch. Diet. 26.— Physa subopaca, Lamark^ Hist. Vert. vol. vi. p. 2. 157- 
— In slow streams, rare. 
Length scarcely half an inch ; pale horn-coloured, glossy ; whorls five, the 
last occupying |ths of the whole length ; apex pointed ; aperture with the 
outer-lip more rounded than the last, and the pillar-lip more recurved an- 
teally. — This shell was first recorded as having been found in Hampshire, by 
Mr Hay. Dr Turton has seen it alive at Naas, in Ireland. Other localities 
have been mentioned, but they are regarded as spurious. — It is a common 
shell from the West Indies. 
Gen. XXXII. PLANORBIS— Cavity of the shell entire, 
sinistral ; the vent, pulmonary cavity, and sexual organs on 
the left side ; tentacula filiform. 
^ Whorls rounded on the margin. 
119. P. -^Whorls four, rounded; concave above; 
mouth suborbicular. 
Cochlea puUa, List. An. Ang. 143. Conch, t. 137- f* 41 — Planorbis 
purpura, MulL Verm. ii. 154. — Helix cornea, lAnn. Syst. i, 1243. 
Penn. Brit. Zool. iv. 134. Mont. Test. Brit. 449 — In ponds and slow 
streams. England. 
Breadth about an inch ; brown, glossy ; lines of growth distinct ; whorls 
above, increasing rapidl}'-, and forming a central cavity ; below, the whorls are 
nearly on the same plane, well defined by the separating line ; last ivhorl pro- 
jecting into the cavity of the aperture. When irritated, the animal pours 
forth a purple fluid from the sides, between the foot and margin of the cloak. 
The H, nana of Pennant is the young of this species. 
120. P. spirorbis. — Whorls five, rounded; fiat above; aper- 
ture suborbicular. 
Mull. Verm. ii. 161. H. spir- Linn. Syst. i. 1244. Mont. Test. Brit. 
455, Suppl. tab. xxv, £ 2 — In pools. 
Breadth about ^^oths of an inch ; nearly equally flat on both sides ; of a 
brown colour ; whorls round, slender, and increasing in size very gradually ; 
deeply divided by the separating line ; aperture nearly round, scarcely inter- 
rupted by the body -whorl. —This species is stated by Montagu as common in 
England. In Scotland it has occurred to us only in Livingstone Woods, 
West Lothian* 
121. P. COW tor to.— Whorls six, compressed ; fiat above, con- 
cave below. 
Helix con. Linn. Syst. i. 1244 — Plan. con. Mull. Verm. ii. 162. — H. con. 
Mont. Test. Brit. 457* tab. xxv. f. 6 — In pools and ditches, not com- 
mon. 
Breadth about y^gths of an inch ; whorls compressed, rounded, even on the 
upper side, narrow, and deeply divided by the separating line ; beneath, a 
large central cavity ; aperture narrow, bent. 
