Paludina. MOLLUSCA. PECTIMBRANCHIA. 315 



3. E. plicattts.—^C 'onical, transversely striated, base angular, sides flattened, 

 central cavity plaited or deeply striated ; aperture oblong.— Cirus plicatus, 

 Sower. Min. Conch, t. cxli. f. 3. — Chalk Marl, Folkstone. 



4. E. perspectivus— Obtusely conical ; spirally striated, central cavity deep, 



exposing one-third of each whorl; aperture transversely oblong Cirus per. 



Mant. Geol. 194. t. xviii. f. 12, 21. Sower. Min. Conch, t. ccccxxviii. f. 1, 2. 

 —In Chalk. 



5. E. depressus — Subdiscoid, concentrically striated ; central cavity wide, 

 exposing a small portion of each whorl ; an angular canal runs round the 

 spire; aperture obtusely angular. — Cirus depressus, Mant. Geol. 195. t. 

 xviii. f. 18, 22. Sower. Min. Conch, t. ccccxxviii. f. 3 In Chalk. 



6. C» granulatus. — Conical; whorls five or six, obscurely quadrangular, or- 

 namented with regular transverse granulated striae. — Mant Geol. 195 Up- 

 per Chalk. 



7- C. Sowerbii. — Conical, spiral, smooth, umbilicate; inner wreaths anchy- 



losed slightly inserted ; aperture indented by the preceding volution. Ver. 



micularia Sower. Mant. Geol. iii. t. xviii. f. 14. 15. — Grey Chalk Marl. 



8. C. Bognorensis — Spiral, last volution much produced, inferior side deep- 

 ly umbilicate — Verm. Bog Alant. Geol. 272. 



Gen. LVI, PALUDINA. — Shell conical, mouth a little long- 

 er than broad ; pillar-lip simple. 



— 267. P. vivipara. — Whorls five or six, rounded ; separating 

 line deep ; apex like a minute tubercle. 



Cochlea maxima, List. An. Ang. 133. t. ii. f. 18. Conch, t. cxxvi. f. 26. 

 — Helix vivipara, Linn. Syst. i. 1247 — Nerita viv. Mull. Verm. ii. 

 182,— Hel. viv. Mont. Test. Brit. 38(3 — Cyclostoma viviparum and 

 achatinum, Drap. Moll. 34, 36. — In the slow running rivers of Eno-. 

 land. 



Length sometimes an inch and a half, the breadth one inch ; olive-green, 

 with three brown spiral bands ; whorls with an abruptly fine apex, irre<nilar- 

 ly wrinkled by layers of growth; the body-whorl occupying about two-thirds 

 of the length of the shell ; aperture nearly semicircular ; pillar-lip a little re- 

 flected, behind which is a small cavity ; operculum corneous ; concentrically 

 striated. Young about ten in number — This varies a little in the shape of 

 its aperture, and in the relative size and distance of the coloured bands. 



268. P. tentaculata. — Whorls five or six, a little rounded ; 

 apex entire. 



Cochlea parva, List. An. Ang. 135. t. ii. f. 19. Conch, t. cxxxii. 32.— 

 Helix tentaculata, Linn. Syst. i. 1249 — Nerita jaculator, Mull. Venn, 

 ii. 185 — Hel. tent. Mont. Test. Brit. 389 — In stagnant waters, Eng- 

 land and Ireland. 



Length half an inch, breadth one quarter, smooth, glossy, horn-coloured, 

 with fine lines of growth ; whorls increasing less rapidly than in the preced- 

 ing species, the body whorl occupying about the half of the length of the 

 shell; aperture ovate, slightly contracted retrally ; pillar- lip a little reflect- 

 ed ; tentacula setaceous, and continually in motion. The young of this spe- 

 cies constitute the Nerita sphcsrica of Muller, and the Cyclostoma simile of Dra- 

 parnaud. 



269. P. acuta. — Whorls five or six, a little rounded, taper- 

 ing ; apex entire. 



