SANGUINOLITES OVALIS. 411 



Sanguinolites ovalis, sp. nov. Plate XL VI, figs. 14 — 17. 



Specific Characters. — Shell below the medium size, inequilateral, transversely 

 ovate, moderately gibbose. The anterior end is short, compressed, its margin 

 rounded. The antero-superior angle well marked. The inferior border is gently 

 convex, more so behind, where it passes upwards to blend with the posterior 

 margin by a gradual curve. The posterior border is obliquely truncate from above 

 downwards and backwards, very gently convex. The postero-superior angle is 

 obtuse and well marked. 



The hinge-line is arched in front, produced and straight behind. The 

 umbones are tumid, small, incnrved, placed in the anterior third of the valve, and 

 not much raised. The lunule and escutcheon are well marked, the latter being 

 separated from the dorsal slope by an erect narrow ridge. 



The valves are obliquely gibbose from the umbones towards the postero- 

 inferior angle. The dorsal slope is compressed ; an almost obsolete diagonal 

 ridge divides a comparatively narrow dorsal slope from the rest of the valve. 



Interior. — The interior adductor muscle-scar is large, round, and deep ; placed 

 just within the antero-superior angle, and bounded behind by a well-marked 

 ridge, which leaves a slit-like depression in casts. Posterior adductor scar not 

 observed. Pallial line entire, and remote from the margin. Hinge not seen in 

 front, but has an inflated margin behind. 



Exterior. — The surface is ornamented with concentric, narrow, close ribs, of 

 irregular size, and often very indistinct, separated by narrow concentric grooves; 

 both of these are even less apparent on the dorsal slope. Fine, close, 

 almost obsolete radiating lines cross these ribs, giving the surface a granular 

 appearance. 



Dimensions. — PI. XLVI, fig. 17, measures — 



Antero-posteriorly . . . .27 mm. 



Dorso-ventrally . . . .12 mm. 



From side to side (estimated) . . .4 mm. 



Local it ij. — England : from shale in the Millstone-Grit series of Holt Head, 

 near Saddle worth, Yorkshire, probably below the third Grit. 



Observations. — This species occurs abundantly in a thin band of shale, at the 

 above-mentioned locality, in association with Lingula, Nuculana stella, Posidoniella 

 Isevis, 8cliizodus antiquus, Nucula gihhosa, and Ostracods. This locality was worked 

 for fossils by Messrs. Barnes and Holroyd, who have done so much good work in the 

 fossiliferous shales of the neighbourhood ; and I am indebted to Mr. Barnes for 

 the material on which I have worked. Unfortunately the shells are nearly always 



