122 CRETACEOUS LAMELLIBRANCHIA. 



with the ventral margin, and an obtuse angle with the dorsal margin. Umbones 

 moderately prominent, curving forwards, bearing a carina which extends to the 

 postero-ventral angle and cuts off a flattened or concave area. Lunule ovate, 

 rather large, nearly smooth. Escutcheon with a sharp edge. 



Ornamentation consists of narrow, rounded, radial ribs, separated by broad, 

 flat interspaces, and crossed at rather distant intervals by strong, narrow, con- 

 centric, lamellar ribs, which give rise to a scale-like projection where they join 

 the radial ribs. The postero-dorsal area has similar concentric ribs, and a strong 

 radial rib near the dorsal margin, and another near the middle of the area with 

 smaller ribs between. 



Measurements : 

















(i) 



(2) 



(3) 



(4) 



(5) 



(6) 



Length 



20 



19 



19 



19 



18 



16 mm, 



Height 



14 



13 



12 



11-5 



12 



11 „ 



(1 — 6) Perna-bed, Atlierfield. 



Affinities. — G. fenestrata appears to be quite distinct from other Cretaceous 

 species of Cardita, but shows some resemblance in form to G. tricarinata, d'Orbigny, 1 

 from the Cenomanian of Le Mans. The hinge and interior are unknown, and the 

 generic position of the species is not free from doubt. Stoliczka remarks 

 that ' G. fenestrata is not unlike a Veneriipis. i 



Type. — From Peasmarsh, in the Museum of the Geological Society, Nos. 

 2182, 2183. 



Distribution. — Perna-bed and Atlierfield Clay of Atlierfield. Atlierfield Beds 

 of Peasmarsh and East Shalford. 



Cardita upwaeensis, sp. nov. Plate XVIII, fig. 5. 



1883. Cardita rotundata ? W. Keeping. Foss., etc. Neoc. Upware aud Brick- 

 hill, p. 121, pi. vi, fig. 7. 



Description. — Shell subtriangular, inflated, height and length nearly equal, 

 inequilateral. Anterior margin rounded, passing gradually into the convex ventral 

 margin. Posterior margin truncated, oblique, not sharply limited from the postero- 

 dorsal margin. Umbones prominent, strongly curved anteriorly, with a rounded 



1 'Pal. Franc. Terr. Oct.,' vol. iii (1844), p. 95, pi. eclxxxiii bis., figs. 5—7; G-ucranger, 'Album 

 Palcout. de la Sarthe' (1867), p. 13, pi. xvi, figs. 19, 20. 



