102 MOLLUSCA FROM THE CRAG. 



3. Rissoa Semicostata. Woodward. Tab. XI, fig. 10. 



Turbo semicostatus (?). Mont. Test. Brit. p. 326, t. 21, fig. 5, 1803. 



— Woodward. Geol. of Norf. t. 3, fig. 19, 1833. 

 Rissoa semicostata. S. Wood. Catalogue 1842. 



— Morris. Catal. Brit. Foss. p. 161, 1843. 



B. Testa brevi, ovato-conicd ; anfractibus quatuor vel quinque, convexis, tumidis; suturis 

 profundis,lonyitudinaliter costidatis ; costulis numerosis in ultimo anfractu dimidiatis ; trans- 

 versim striatis ; apertur a sub rotunda ; labro intus dentato. 



Shell short, small, and conical, with four or five convex and tumid volutions ; 

 suture deep and distinct, longitudinally costated ; costas disappearing on the lower 

 half of the volution, transversely striated ; strias visible between the ribs and over 

 the base ; left lip slightly reflected over a small umbilicus ; outer lip thickened, and 

 dentated within. 



Axis, yo °f an mcn j diameter, yj. 



Locality. Mam. Crag, Bramerton. ? Recent, British Seas. 



This is a rare shell in my cabinet, and Woodward speaks of it also as not being 

 abundant. It has about twenty ribs upon the last volution, and has an obtuse apex. 

 It is, I presume, the T. semicostatus of Woodward, as far as can be determined from 

 his indifferent figure, but probably not the T. semicostatus of Montague. I would 

 suggest the name of curticostata for this species, if it be really distinct. In my Crag 

 specimens the costae are visible upon the upper volutions. 



4. Rissoa vitrea. Mont. Tab. XI, fig. 3. 



Turbo vitreus. Mont. Test. Brit. p. 321, t. 12, fig. 3, 1803. 



Cingula vitrea. Flem. Brit. An. p. 308, 1828. 



Rissoa (?) vitrea. S. Wood. Catalogue 1842. 



Cingula vitrea. Thorpe. Brit. Mar. Conch, p. 182, 1844. 



B. Testa turritd, elongatd, subcylindraced, lavissimd, politd, vitrea, pellucidd, alba 

 tenui fragili ; anfractibus 4 — 5, parum convexis; suturis prof undis ; apice obtusiusculo ; 

 aperturd ovatd ; labro simplici. 



Shell small, turriculate, subcylinclrical, smooth, glossy, thin, white, and semi- 

 transparent, with four slightly convex volutions ; suture distinct and deep ; apex 

 rather obtuse ; aperture ovate, contracted at the upper part ; peristome sharp, con- 

 tinuous ; outer lip plain ; inner lip covering the umbilicus. 



Axis, •§• of an inch. 



Locality. Cor. Crag, Sutton. Recent, British Seas. 



This elegant little fragile shell is at present rare, and appears perfectly identical 

 with the recent British species. It differs materially, in its vitreous texture, its 

 glossy and subhyaline appearance, from the general character of the shells of this 

 genus, which are usually opaque, and more or less externally ornamented. 



