GASTEROPODA. 35 



and in the young shell it is particularly large. In some specimens the striae are 

 very conspicuous, while in others they are somewhat indistinct ; they may, however, 

 be traced in every specimen. The left lip extends some way over the body of the 

 shell, and there is a prominent ridge on the edge of the columella, as pointed out 

 by Mr. J. Sowerby in ' Min. Conch.,' corresponding in these characters with the 

 genus Nassa, but it has a large and open aperture, with a plain and simple outer 

 lip, which is free from denticulations. It may be considered as a rather aberrant 

 form connecting the two genera. 



Buc. ovum, Turt., has hitherto been represented and described as a perfectly 

 smooth shell, and considered, in consequence, as a new species, distinct from B. 

 Dalei, with which it agrees in all other characters. Professor E. Forbes, however, 

 has informed me that Mr. M'Andrew has detected some faint traces of striae upon 

 a specimen of B. ovum in his possession. It may then, I think, be fairly presumed 

 as identical with B. Dalei of the Red Crag, and its extreme rarity be looked upon 

 as the dying out of a species once exceedingly abundant in this country ; and in thus 

 becoming extinct, may not its want of, or rather its faint and imperfect striae be 

 from failure in vigour in those organs necessary for such distinction, consequent 

 upon the approaching demise of the species ? 



2. Buccinum tjndatum. Linn. Tab. Ill, fig. 12, a — d. 



Buccinum undatum. Linn. Syst. Nat. p. 1204, 1/66. 



— striatum (?). Penn. Brit. Zool. iv, p. 121, 1/76. 



— undatum. Brown. Illust. Brit. Conch, pi. 49, fig. 8, 1827. 

 Anglicanum (?). - - - pi. 49, fig. 11. 



— tenerum. J. Sow. Min. Conch, t. 486, fig. 3, 1825. 



— Nijst. Coq. foss. de Belg. p. 571, pi. 43, fig. 9, 1844. 



— undatum. S. Wood. Catalogue 1842. 

 Tritonium undatum. Lovin. Ind. Moll. Scand. p. 12, 1846. 



— Bale. Hist, and Antiq. of Harwich, pi. 10, fig. 8, 1730. 



B. Testa ovato-conicd, ventricosd, striata, cosfatd, undulatd ; anfractibus convexis ; 

 aperturd ovatd, labro sinuato, canali brevissimo aperto. 



Shell ovato-conical, ventricose, generally thin, with, sometimes without, undulate 

 costae ; whorls convex ; aperture ovate, with a thickened and slightly situated outer 

 lip ; base emarginate ; canal short and open. 



Axis, 3 inches. 



Locality. Cor. Crag, Ramsholt. 



Red Crag, Butley, Newbourn, Sutton, and Walton. 



Mam. Crag, Bridlington. Recent, British and North Seas. 



This shell first appears in the Coralline Crag, where, however, it is by no means 

 abundant. In the Red Crag it becomes more so ; but the greater number of the 

 specimens, being much reduced in substance, are fragile, and difficult to obtain ; 

 the outer coating having been in some instances entirely removed, its peculiarly 

 striated markings are thereby obliterated. Some specimens so precisely resemble 



