516 MOLLUSCA. PECTINIBRANCHIA. Paludina. 
Cyclostoma acutum, Drap. Moll. 40. t. i. f. 23.—-Turbo Leachii, Shep- 
pard^ Linn. Trans, xiv. 152. — Cyc. acutum, Turton^ Zool. Journ. ii. 
565. — In stagnant ditches, England. 
Length from 2 to 3 lines, breadth nearly |ds less ; diaphanous, of a horn 
colour ; the body-whorl occupies about one-half of the shell ; aperture ap- 
proaching to semicircular ; pillar-lip a little reflected, with a slight cavity be- 
hind. This shell is subject to some variety in its growth. The specimens 
in my possession from Bristol, were communicated by Mr Thomas Drum- 
mond. 
EXTINCT SPECIES. 
1. P. Jluviorum . — Whorls four to six, convex ; shell about twice the length 
of the aperture ; lines of growth rather sharply conspicuous, giving the sh^ell 
a finely striated appearance. — Vivipara fluv. Sower. Min. Conch, t. xxxi. f. 1. 
— Mantell., Geol. Suss. 45. t. xvii. f. 56. — In Limestone above and below the 
Iron sand. 
2. P. extensa . — Whorls four or five, subconvex, lower part rather angular; 
inner lip swelling a little at the umbilical side, outer lip extended outwards ; 
shell about twice the length of the aperture. — Viv. est. Sower. Min. Conch, 
t. xxxi. f. 2. — With the preceding. 
3. P. lenta.— Smooth ; whorls five or six, scarcely angular ; lines of growth 
occasionally conspicuous ; aperture nearly round, entire.-' Sower. Min. Conch, 
t. xxxi. f. 3. — London Clay., at Hordwell and Barton. 
4. P. concinna — Shell rather conical ; whorls four or five ; slightly convex ; 
lower part rather angular. — Sower. Min. Conch, t. xxxi. f. 4, 5. — Barton 
Cliff. 
5. P. suloperta . — Whorls five, convex, with a depressed line along the up- 
per part ; 'a little wrinkled ; outer lip folding partly over the upper part of 
the aperture ; shell about twice the length of the aperture. — Sower. Min. 
Conch, t. xxxi. f. 6 — Crag, Holywells. 
The three preceding species probably belong to the marine genus Cingula, 
nor is it certain that the two following are true Paludince. 
6. P. elongata . — Ovato lanceolate, .smooth ; whorls five, convex ; aperture 
elongated. Soiver. Min. Conch, t. nix. f. 1, 2.— Weald Clay. 
7. P. carimfera — Ovato-conical, smooth ; whorls four, convex, the upper 
two bounded by a linear keel at the lower edge. — Sower. Min. Conch, t. 
Dix. f. 3. — Purheck Limestone. 
Gen. ampul lari a. —S hell globose, pillar-lip prominent 
and reflected. 
1. A. acuta Ventricose, smooth, with a small acute spire ; pillar-cavity 
small, half closed ; aperture ovate, elongated. — (Helix mutabilis, Brander, f. 
58, 59.) Sower. Min. Conch, t. cclxxxiv. three upper figures — London Clay. 
2. A. joa^w/a.-Ventricose, smooth, ivith a short spire; pillar-cavity large, 
open, lined with a spiral adpressed plate ; aperture obovate, — (Helix muta- 
bilis, Brander, f. 57.) Soiver. Min. Conch, t. cclxxxiv. two middle figures. — 
London Clay, Barton. — This species seems nearly related to Turbo quadrifas- 
ciatus. 
3. A. segaretina ^Ventricose, short, spire small, acute, with sharp trans- 
verse striae ; pillar-cavity covered, small, half filled by a spiral plate ; aper- 
