320 MOLLUSCA. PECTINIBRANCHIA. Nauca. 



nous lines ; pillar-cavity very large. This species has occurred only to Mr 

 Donovan. 



276. N. tuberosisshna. — Whorls four, marked with four spi- 

 ral broken tubercular ridges. 



Nerita tub. Mont. Test. Brit. Sup. 150. t. xxix. f. 5.— At Dunbar, Mr 

 Laskey. 



Breadth about ^th of av. inch; pellucid, white; upper volutions small ; 

 pillar-cavity large. 



277. N. sulcata. — Whorls four, with remote oblique trans- 

 verse striae. 



Nerita sal. Turton. Conch. Diet. 124. fig. 56, 57 N. glabrissimus, 



Brown., Wern. Mem. ii. 532. t. xxiv. f. 12. — Two specimens found in 

 Dublin Bay by Dr Turton. 

 Breadth ith of an inch ; globular, semitransparent, bluish-white; whorls 

 swollen, well defined ; pillar-lip flat, projecting a little in the middle over 

 the cavity behind, which is long and deep. 



278. N. paUklula. — Whorls three, pillar-lip with a wide 

 groove leading to the cavity. 



Ner. pall. Don. Brit. Sh. t. xvi. f. i. Mont. Test. Brit. 468— Turbo pal- 

 lidus and puteolus, Turt. Conch. 192. — Among sea weeds, about low 

 water-mark, common. 

 Length i an inch, breadth |ths ; yellowish-brown ; whorls rounded, with 

 a grooved separating line, the upper ones small, lateral, and little produced, 

 slightly wrinkled by the layers of growth ; pillar-cavity deep, the retral ex- 

 tremity of the lip partly folded over it ; operculum with diverging wrinkles. 



279- N. lacuna. — Whorls four ; pillai"-lip with a narrow 

 groove leading to the cavity. 



Ner. lac. Mont. Test. Brit. 428. t. xiii. f. 6 — Turbo lacuna, Tiirt. Conch. 

 Diet. 193. t. XXV. f. 87, 89 — On the English shores, rare. 

 This shell bears a very close resemblance to the preceding. Judmng from 

 an authentic example which I received from Mr Montagu, it chiefly differs 

 in the less enlargement of the body-whorl towards the aperture, the second 

 whorl being better defined, the pillar-groove narrower, and the anteal cur- 

 vature of the lip more restricted : there are likewise some faint traces of spi- 

 ral strioe. 



EXTINCT SPECIES. 



1. N. glaimnoides — Nearly globose spire, rather elongated ; pillar-cavity 

 simple, partly covered ; upper part of each whorl slightly depressed. — Smver. 

 Min. Conch.t. v. three upper figures, and t. cccclxxix. f. 4. — London Clay and 

 Suffolk Crag. 



^. 'ii . similis. — Shell rather rhomboidal ; spire short; pillar cavity divided 

 by a spiral projection ; aperture slightly angular a.hove.— Sower. INIin. Conch, 

 t. V. two middle figures. — London Clay. 



3. N. depressa Nearly globose, subumbilicated ; upper part, and the side 



of each whorl, flattened, so as to appear nearly square ; columella depressed 

 beneath ; aperture angular at the upper part. — Sower. Min. Conch, t. v. lower 

 figures. — Crag-marl. 



