Natica. MOLLUSCA. PECTINIBRANCHIA. 310 



6. N. costata. Hemispherical ; spire conspicuous, impressed ; whorls trans- 

 versely costated ; costse thin, sharp, numerous ; aperture expanded, orbicu- 

 lar ; columellar lip prominent, obtuse. Soiver. Min. Conch, t. cccclxiii. f. 5, 

 6. Oolite, Ancliff. 



7. N. spirata. Semiglobose, smooth ; spire small, partly immersed ; upper 

 parts of the whorls flat, when old, concave ; aperture transversely oval — 

 .Soiver. Min. Conch, t. cccclxiii. £ I, 2. Mountain Limestone. 



8. N. I possess some imperfect specimens of a species differing 



from the preceding in size, and in the spire being larger. From the Tran- 

 sition Limestone of Cork. 



9. N. striata. Spire slightly produced ; whorls flat, crossed by numerous 

 narrow rounded ribs. I found an imperfect specimen of this shell in Carboni- 

 ferous Limestone at Corry,lArran 5th June 1807. It bears a close resemblance 



to the recent Nerita polita. 



Gen. LVIII. NATICA. — Pillar-lip entire, not entering the 

 aperture, with a cavity or callus behind. 



— 272. N. glaucina. — Whorls six, smooth, pillar-lip thick and 



reflected, forming a large and deep cavity. 



Cochlea rufescens, List. An. Ang. 163. t. iii. f. 10, Conch. 568. (.119.— 

 Nerita glaucina, Linn. Syst. i. 1251. Mont. Test. Brit. 469. Inhabits 

 deep sandy bays, common. 



Length about an inch and a half, breadth rather less ; whorls little elevat- 

 ed ; apex pointed ; colour brownish white, with interrupted bands of brown 

 on the upper volutions; outer lip considerably advanced at its junction with 

 the body ; operculum divergingly striated. Mr Hog has demonstrated, that 

 the substance known under the name of Flustra arenosa, is the nidus of this 

 species, in the cells of which the eggs are deposited. Linn. Trans, xiv. 318. 

 The Nerita pellucida and alba of Adams, ib. iii. 67- are probabl)' the fry of 

 this species. 



273. N. nitida. — Whorls five ; pillar cavity half closed. 



Nerita nit. Don. Brit. Shells, 144. Mont. Test. Brit. Sup. 149. On 

 different parts of the coast, not common. 



Diameter scarcely half an inch; glossy, white ; spire short ; whorls nearly 

 flat, with the separating line nearly obliterated. 



274. N. riifa. — Smooth, purplish, with a white band round 



the top of the volutions, and two others on the body-whorl. 



Nerita rufa, Mont. Test. Brit. Sup. 150. t. xxx. f. 3. English and Scot- 

 tish coast, rare. 



Breadth about half an inch ; pillar-lip forms a large projection over the ca- 

 vity behind, producing an indenture on each side of it. The second whorl 

 in this is larger in proportion than in N. glaucina. 



— 275. N. intrlcata. — Pillar-cavity furnished with two spiral 



ridges and two grooves. 



Nerita in. Don. Brit. Shells, t. clxvii. N. canrena, Mont. Test. Brit. 

 Sup. 148. Weymouth, rare. 



Length about half an inch ; smooth, livid, with bands of sagittate ferrugi- 



