Or 
we 
CRETACEOUS LAMELLIBRANCHIA. 
SucuLLmA Frrront (Pictet and Campiche), 1866. Plate X, figs. 4 a—d, 5—7. 
1857. Arca Ropinanpina, FF. J. Pictet and HB. Renevier (non d’Orbigny). Foss. 
Terr. Aptien, &v. (Matér. Pal. Suisse, ser. 1), 
p. 105, pl. xv, fig. 4. 
1866. — Frrront, #. J. Pictet and G. Campiche. Foss. Terr. Crét. de Ste. 
Croix (Matér. Pal. Suisse, ser. 4), pt. 8, pp. 455, 471. 
1871. — — F. Stoliczka. Paleont. Indica, Cret. Fauna S. India, vol. 
ill, p. 843 (? Drigonoarca). 
Description.--Shell more or less oblong, rather inflated, equilateral or shghtly 
inequilateral. Anterior margin evenly rounded, passing gradually into the ventral, 
which is parallel to the dorsal margin, but curves toward the postero-ventral angle. 
Posterior margin nearly straight, oblique. Umbones moderately large, nearly 
median, separated by only a small space, with a very sharp carina, curved, and 
passing to the postero-ventral angle. The postero-dorsal area is sharply de- 
pressed, and near its ventral third bears another carina. Hinge-line rather short ; 
area small, with many ligament-grooves. Ornamentation consists of many fine 
concentric grooves, and on the antero-dorsal part of the shell of a few radial ribs ; 
postero-dorsal area with many radial ribs. Central teeth (about ten) transverse ; 
lateral teeth longitudinal. Interior not seen. 
Measurements : 
(1) (2) 
Length . é 5 19°5 : : 14. mm. 
Height . : : 15 ; a eee 
Thickness : : 12°5 ; g BPSY 55 
Affinities —This form is probably only a local variety of Arca Kobinaldina, 
dOrbieny ; it differs from that in being less elongate posteriorly. In d’Orbigny’s 
figure of A. Robinaldina the ventral margin has a greater curvature than in any of 
the specimens which I have seen in the Paris museums. Arca Cornueliana, 
VOrbigny, is distinguished from C. Fittont by the absence of the sharp carina. 
Arca xquilateralis, Briart and Cornet, is very similar to C. Fittoni, but it appears 
to be proportionately shorter, and to have the anterior margin less curved. 
Distribution.—Crackers of Atherfield. Atherfield Beds of East Shalford. 
CucULLaA vaGANs, Keeping, 1883. Plate X, figs. 8—10. 
1883. Cucunnma vaaans, W. Keeping. Foss., &c., Neoc. Upware and Brickhill, 
p. 151, pl. vi, fig. 8. 
1883. — ERRANS, Keeping. Ibid., pp. 38, 34, 86, 65 (nom. nud.). 
