92 



ORETACEOTTS LAMELLIBRANCHIA. 



Types. — From the Neocomian of Seignelay, near Auxerre. The type of 

 P. Flttoni is from the Perna-bed of the Isle of Wight. 



Distribution. — Lower Greensand (Perna-bed) of Atherfield. Tealby Limestone 

 (zone of Belemnites hrunsvicensis) of North Willingham. 



Pig. 18. — Perna Rieordeana, d'Orbigny. Tealby Limestone, North Willingham. Sedgwick Museum. 

 Left valve, x f . 



Peb,na Rauliniana, d'Orbigny, 1846. Plate XII, figs. 6, 7a, b, 8, 9. 



1846. Perna Rauliniana, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, p. 497, 



pi. cccci, figs. 4, 5. 

 1850. — — d'Orbigny. Prodr. de Pal., vol. ii, p. 138. 



1852. — — F.J. Pictet and W. Eoux. Moll. Foss. Gres verts de 



Geneve, p. 497, pi. xli, fig. 4. 



1854. J. Morris. Cat. Brit. Foss., ed. 2, p. 179. 



1855. — — G. Cotteau. Moll. Foss. de l'Yonne, p. 107. 



1869. — F. J. Pictet and G. Campiche. Foss. Terr. Cret. Ste. 



Croix (Mater. Pal. Suisse, ser. 

 5), p. 100, pi. clx, figs. 1, 2. 



Description. — Shell of moderate convexity, valves nearly equal, compressed 

 posteriorly, sub-rhomboidal, oblique, much higher than long; postero-ventral 

 margin rounded, anterior margin slightly concave, posterior margin slightly convex, 



