PROSOBRANCHIATA. 181 



In a fossil state, the genus first appears in the cretaceous formations, in which five or 

 six species are stated to occur ; but during the tertiary epoch, the species became much 

 more numerous. More than forty have been described from the eocene strata, and a 

 still greater number from the more recent deposits. From the English eocene strata, 

 four species have been noticed ; of these, three, described by Mr. Sowerby in ' Mineral 

 Conchology, 5 appear to be confined to this country ; the fourth occurs at Bracklesham, 

 and is identical with a species abundant in the Paris basin. Three additional species 

 are now described for the first time. 



No. 118. Mitra scabra. Sowerbg. Tab. XXIV, fig. G a — c. 



Small latticed Lymington whelk, Pet. 1764. Gazopliyll., t. 73, fig. 9. 



Buccinum scabriculum, Soland. (non Gmel.) 1766. Brand. Foss. Hant., p. 15, fig. 20. 



Mitra scabra, Sow. 1823. Min. Con., vol. iv, p. 142, t. 401. 



— — Morris. 1843. Cat. Brit. Foss., p. 151. 



I)' Orb. 1850. Prod, de Paleont., vol. ii, p. 355, No. 313. 



— — Morris. 1854. Cat. Brit. Foss. (2d edit.), p. 258. 



M. testa ovato-acutd, costulis longitudinalibus et lineis transversis sese decussantibus 

 scabratd, ad basin profunde emarginatd .- spird conicd, apice obtusiusculo .• anfractibus 

 convexis, marginibus posticis tenuibus ; aperturd elongato-ovali, postice angustald ; labro 

 incrassato, sub-marginato, intus crenulato ; columella quadri-plicatd, plicis dista?itibus,fere 

 transversis ; labii area plicif era incrassatd. 



Shell ovately oblong, slightly ventricose, deeply notched at the base, with a conical 

 spire, terminating in a small, slightly obtuse apex, formed of two smooth, nearly round, 

 embryonal volutions ; whorls seven or eight, exclusive of the embryo, and covered 

 with irregular longitudinal ridges, and conspicuous lines of growth, decussated by 

 sharp, transverse, raised lines slightly thickened at the points of decussation, roughen- 

 ing the surface of the shell ; the posterior margins are thin, and pressed against the 

 preceding whorls. The aperture is of a lengthened oval shape, narrowed posteriorly ; 

 the outer lip sharp and thin in the young shell, but irregularly thickened at maturity, 

 and presenting an obscure, slender, raised border along the outer edge, and a blunt 

 triangular tooth-like callus on the inner edge, near the posterior extremity ; the colu- 

 mella is furnished with four distant, nearly transverse folds, of which the anterior one 

 is much the smallest ; and some specimens also present one or two obscure transverse 

 lines towards the posterior part of the columella. The inner lip is very narrow, and 

 much thickened where the folds are placed. Owing to the great depth of the notch, 

 the base of the shell is more bent backwards than is usually the case in the fossil 

 Mitra, and presents the prominent crest or ridge which, as we have seen in the 

 Volutes, always accompanies a deep notch. 



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