122 CJRKTACEOUS LAMELLTBRANCHIA. 



with the veiiti'al margin, and an obtuse angle with the dorsal margin. Umbones 

 moderately prominent, curving foi'wards, bearing a carina which extends to the 

 postero-ventral angle antl 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. 



(1 — 6) Perwa-bed, Atherfield. 



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

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

 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. fenestraia is not unlike a Venerupis.' 



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

 2182, 2183. 



Distribufiun. — I'cnia-Xwd and Atherfield Clay of Atherfield. Atherfield WeiU 

 of Peasmarsh and East Shalford. 



Cardita upwarensts, s]). nov. Plate XVIII, fig. 5. 



1883. Cakdita eotundataV W. Keejiincj. Foss., etc. Ncoe. Upwarc aud Brick- 

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



Description. — Shell subtriangular, inflated, height and length neai'ly e(|ual, 

 inequilateral. Anterior margin i-ounded, 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. Fran9. Terr. Grot.,' vol. iii (1844), p. 95, pi. cclxxxiii his., tigs. 5—7; Guorauger, ' Allmiu 

 Palcont. de la Sarthe' (18G7), p. 13, pi. xvi, figs. Ifl, 20. 



