90 



CRETACEOUS LAMELLIBRANCHIA. 



Peena Ricordeana, d'Orbigny, 18-16. Text-figures 16-18. 



1846. Pekna Ricordeana, A. tVOrbigny. Pal. Franc;. Terr. Cret., vol. iii, p. 494, 



pi. cccxcix, figs. 1 — 3. 

 1850. d'Orbigny. Prodr. de Pal., vol. ii, p. 82. 



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



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



1858. — F.J.PirtetandE.Renevier. Foss. Terr. Aptien (Mater. 



Pal. Suisse, ser. 1), p. 125. 

 F. J. Pictet and G. Oampiche. Foss. Terr. Cret. Ste. 

 Croix (Mater. Pal. Suisse, ser. 

 5), p. 93, pi. clvii, fig. 1. 

 Fittoni, Pictet and Campiche. Ibid., p. 95, pi. clvii, fig. 2. 

 Ricordiana, W. Keeping. Foss., etc., Neoc. Upware and Brickhill, 



p. 150. 

 Eicordeana, A. Wollenuiiin. Die Biv. u. G-astrop. d. deutsch. u. 

 holliLnd. Neocorus (Abbandl. d. k. 

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

 31), p. 61. 



1869. 



1869. 

 1883. 



1900. 



Fig. 16. — Perna Ricordeana, d'Orbigny. Lower Greensand (Perna-bed) , Atherfield. Museum of Practical 

 Geology, No. 12351. Left valve, x }. 



Description. — Shell large, thick, sub-quadrate, compressed; left valve more 

 convex than the right. Posterior margin slightly convex or nearly straight and 

 forming with the hinge-line an angle which is rather greater than a right-angle. 



