Neretina. MOLLUSC. PECTINIJ3RANCH1A. 321 



4. N. patula Hemispherical, smooth, spire small, depressed ; pillar cavi- 

 ty open, containing a spiral ridge. — Sower. Min. Conch, t. ccclxxiii. three lower 

 figures — Suffolk Crag. 



5. N. striata Subhemispheroidal, smooth ; spire small, depressed ; pillar 



cavity open ; base concentrically striated — Sower. Min. Conch, t. ccclxxiii. 

 two upper figures. — London Clay. 



6. N. cirrifornm Globose ; whorls slightly compressed laterally ; spire 



conspicuous ; pillar cavity large, deep, open ; pillar lip thick, with a sinus in 

 the middle ; aperture small, oblong — Sower. Min. Conch, t. cccclxxix. f. 1. 

 —Suffolk Crag. 



7- N. Iwmiclausa. — Subglobose ; spire small, conical, pointed ; cavity half 

 closed by the upper part of the pillar lip ; aperture oval. — Sower. Min. Conch. 

 t. cccclxxix. f. 2. — Crag. 



8. N. sigaratina — Much depressed ; pillar cavity large, filled with a lenti- 

 cular callus — Sower. Min. Conch, t. cccclxxix. f. 3 London Clay. 



Gen. LIX. NERETINA. — Pillar lip broad, flat, entire ; outer 

 lip patulous. 



— 280. N.Jluviat'dis.— Transversely oval, outer lip thin. 



Nerita fluviatilis, List. An. Ang. 13G. t. ii. f. 20. Conch, t. 607- f. 43 



Linn. Syst. 1253. Mont. Test. Brit. 470. — On stones in slow running 

 rivers in England and Ireland. 



Length |ths of an inch, breadth §ths ; variously streaked or spotted with 

 purple white and brown ; the whorls rounded, the upper ones small ; slight- 

 ly striated across by the lines of growih ; pillar lip white ; lid yellow, with 

 a lateral tooth behind, imbedded in the foot. 



EXTINCT SPECIES. 



1. N. concava. — Obovate, with a prominent obtuse spire ; upper part of 



each whorl concave ; aperture semicircular ; lip entire Soider. Min. Conch. 



t. ccclxxxv. £ 1-8 — In various strata from the London Clay to the Crag. 



2. N. uniplkata.— Subglobose, with a concealed spire, and one plait upon 

 the rather convex pillar lip — Sotver. Min. Conch, t. ccclxxxv. f. 9. 10. — Lon- 

 don Clay. 



TROCHUSID.E. 



Gen. LX. TROCHUS. — Base flat or concave; aperture 

 transversely depressed. 



* Pillar perforated. 



-281. T. Magus. — Spire subdepressed ; whorls six, flattened 

 above towards the deep separating line ; the last whorls tuber- 

 culated. 



T. planior, List. Conch, t. C41. 31 — T. Magus, Linn. Syst. i. 1228. 

 Mont. Test. Brit. 283 — In deep water, not common. 

 VOL. I. v 



