316 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. 

 5G5 — 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- 

 mono. 



EXTINCT SPECIES. 



1. P. fluviorum. — Whorls four to six, convex ; shell about twice the length 

 of the aperture ; lines of growth rather sharply conspicuous, giving the shell 

 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. externa — Whorls four or five, subconvex, lower part rather angular ; 

 inner Up 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. suboperta. — 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. Sower. Min. Conch, t. Dix. f. 1, 2. — Weald Clay. 



7. P. carinifera. — 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. — Purbeck Limestone. 



Gen. AMPUL L ARIA. — Shell 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. patula.-Yentricose, smooth, with a short spire ; pillar-cavity large, 

 open, lined with a spiral adpressed plate ; aperture obovate,— (Helix muta- 

 bilis, Brander, f. 57.) Sower. 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 strise ; pillar-cavity covered, small, half filled by a spiral plate ; aper- 



