UNICARDIUM. 163 



Unicardium vectense, sp. nov. Plate. XXV, figs. 8 — 11. 



Description. — Shell thin, much inflated, oval or slightly subquadrate, inequi- 

 lateral, the anterior part rather larger than the posterior part; length a little 

 greater than height. Antero-dorsal margin short, nearly straight. Anterior 

 margin rounded, making an obtuse angle with the antero-dorsal margin, and 

 curving rapidly to join the moderately convex ventral margin. Posterior margin 

 rounded, slightly truncated. Postero-dorsal margin slightly convex. Umbones 

 prominent, contiguous, curving inward and forward. Ornamentation consists of 

 numerous, strong, somewhat irregular, concentric ribs. Ligament in a long, 

 narrow groove. Teeth absent or poorly developed. 



Measurements : 



(1) (2) (3) (4). 



Length 20 . 18 . 16 . 12 mm. 



Height 19 . 17 . 15 11-2 „ 



(1 — 4) Crackers, Athcrfield. 



Affinities. — The shell is relatively higher, the umbones more prominent, and 

 the ribs rather stronger than in TJ. Ebrayi, de Loriol. 1 



Distribution. — Lower Greensand: Crackers of Atherfield, Perna-hed of Sandown, 

 and Ferruginous Sands of Shanklin. 



Unicardium, sp. Plate XXV, fig. 12. 



A specimen of Unicardium from the Upper Greensand of South Devon 2 was 

 collected by Sir H. T. De la Beche and is now in the Museum of the Geological 

 Society, No. 1580. It resembles U. vectense, but the umbones are not so promi- 

 nent and the ribs are smaller, more numerous, and more regular. 



Unicardium? gaultinum (Pictet and Bovx), 1852. 



1852. Coebis gaultina, F. J. Pictet and W. Rouv. Moll. Foss. Ores verts de 



Greueve, p. 448, pi. xxxiv, fig. 4. 

 I860. Fimbria F. J. Pitfet and G. Campiche. Foss. Terr. Oct. Ste. 



Croix (Mater. Pal. Suisse, ser. 4), 

 p. 282, pi. exxii, figs. 3, 4. 

 18^1- F. StoliczJca. Palseont, Indica, Cret. Fauna S. India, 



vol. iii, p. 252. 

 1875. Corbis A. J. Juices-Browne. Quart, Journ. Ceol. Soc, vol. xxxi, 



p. 300, pi. xv, fig. 9. 



1 ' Gault de Cosne' (1882), p. 70, pi. viii, figs. 13-16. 



2 Probably from near Sid mouth or Blackdown. 



