104 CRETACEOUS LAMELLIBRANCHIA. 



Type. — From the Neocomian of Brienne (Aube). 



Distribution. — Pema-bed of East Shalford. Atherfield Bods of Sevcnoaks. 



Astakte sinuata, d'Orbigny, 1844. Plate XIV, figs. 7 — 9. 



1844. Astaete sinuata, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, p. 69, pi. 



cclxiv, figs. 1 — 3. 

 1850. d'Orbigny. Prodr. cle Pal., vol. ii, p. 118. 



1856. F. J. Pictet and E. Benevier. Foss. Terr. Aptien (Mater. 



Pal. Suisse, ser.l), p. 89, 

 pi. x, fig. 3. 

 1866. F. J. Pictrt and G. Camjnche. Foss. Terr. Oct. Ste. 



Croix (Mater. Pal. 



Suisse, ser. 4), p. 311. 



1871. — F. Stoliczlea. Palseont. Indica, Cret. Fauna S. India, 



vol. iii, pp. 251, 285. 

 1895. — Q. Maas. Zeitsclir. d. deutsch. geol. Gesellseh., vol. 



xlvii, p. 261. 

 1900. — A. Wollemann. Die Biv. u. Gastrop. d. deutsch. u. 



holliind. Neocoms (Abhandl. d. k. 

 preussisch.. geol. Land., N. F., pt. 31), 

 p. 100. 



Description. — Shell sub-quadrate, rounded ventrally, truncated posteriorly, 

 longer than high, slightly or moderately inequilateral, much compressed. A furrow 

 extends from just behind the umbo to the sinuosity on the posterior margin, and 

 cuts off a triangular, flattened, postero-dorsal part of the valve. Antero-dorsal 

 margin nearly straight. Anterior margin rounded, passing gradually into the 

 curved ventral margin. Posterior margin with a sinuosity above the postero- 

 ventral angle. Postero-dorsal margin straight or slightly concave, longer than the 

 antero-dorsal margin, and forming an angle with the posterior margin. Umbones 

 pointed, inconspicuous. Lunule and escutcheon long, narrow, with sharp edges 

 which have tooth-like projections where the ribs end. 



Ornamentation consists of rounded, concentric ribs separated by shallow 

 furrows. The ribs are rather stronger on the posterior than on the anterior part 

 of the shell, and are sinuous where they cross the posterior furrow. Smaller ribs 

 are present on the main ribs and furrows. 



Measurements : 



(i) (2) 



Length 10 15 mm. 



Height . . . 14-5 . . 14 „ 

 Thickness . 4* 



(1, 2) Crackers, Atherfield. 



