264 PYRAMIDELLID^. 



O. UNIDENTATA, MoiltagU. 



Solid, smooth, bluish white ; body not equal to the spire in 

 length, for the most part more or less angulated at the peri- 

 phery ; whorls a little convex, of quick longitudinal increase ; 

 apex blunt; mouth short, subrhomboidal ; throat smooth; pillar 

 lip perpendicular, reflected, with a prominent horizontal tooth- 

 like fold : no umbilicus. 



Plate XCV. fig. 7, 8. 



Turbo unidentutus, IMont. Test. Brit. vol. ii. p. 324. — Turt. Conch. Diction. 



p. 222. 

 Voluta unideidata, Maton and Rack, Trans. Linn. Soc. vol. viii. p. 121. — 



Dii.LW. Recent Shells, vol. i. p. 508. 

 Odostomia plicaia, Fleming, Brit. Animals, p. 310. — Brit. Marine Conch, p. 

 172 (not of Syst. Index). 

 „ U7udentata, Brit. Marine Conch, p. 172 (not of Syst. Index). ■ — 



Brown, Illust. Conch. G. B, p. 21. — Jeffreys, 

 Ann. Nat. Hist, new ser. vol. ii. p. 340. — Alder, 

 Cat. Moll. Northumborl. and Durh. p. 50. 



Whether it be the nature of the shell to vary in shape 

 more than its congeners, or that a greater familiarity with 

 the species has increased our knowledge of the several 

 aspects it is wont to assume, we know not, but the study 

 of a large number of examples enables us to assert, that it 

 ranges in shape from almost conical with a subangulated 

 periphery (its more ordinary form in the cabinets of col- 

 lectors) to turreted-conical with its periphery rounded. Its 

 solidity appears a constant character ; it is smooth, glossy, 

 very little transparent, and of a bluish white. There are 

 six shortish whorls, that are simply and moderately con- 

 vex, of tolerably fast longitudinal increase, and very clearly 

 divided by a strong but simple and not very oblique suture. 

 The nucleus is peculiarly oblique and prominent, and appears 

 to be composed of more than one coil. The apex is blunt- 

 ish, and when it is filled by the animal has a blackish cast. 



