74 CRETACEOUS LAMELLIBRANCHIA. 



bridge Greensand (indigenous). Chloritic Marl of Maiden Bradley, Devizes, 

 Isle of Wight, Urchfont (Wilts), Holybourne (Hants), and Eastbourne. Chalk 

 Marl (zone of Scldoenbachia varians) of the Isle of Wight, Folkestone, Hunstanton, 

 Lincolnshire, and Yorkshire. Totternhoe Stone of Fulbourn and Burwell. Zone 

 of Holaster subglobosus (above Totternhoe Stone) of Eversden (Cambs.). 



Family— PERNIM), Zittel. 



Genus — Geevillia, M. J. L. Defrance, 1820. 

 ('Diet. Sci. nat.,' vol. xviii, p. 502.) 



Geevillia sublanceolata (d'Orbigny), 1850. Plate X, figs. 14 — 16 ; Plate XI, 



fig. 1. Text figures 7, 8. 



1826. Gervillia aviculoides, J. de C. Sowerby. Min. Conch., vol. vi, p. 16, pi. 



dxi, figs. 1, 2, 3, 5 (not 4), [lion Perna 

 aviculoides, Sowerby, 1814]. 



1845. E. Forbes. Quart. Jouru. Geol. Soc.,vol. i, p. 246. 



— Avicula lanceolata, — Ibid., p. 247, pi. iii, fig. 8. 



1850. — sublanceolata, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 119. 



1853. Gervilia alpina, F. J. Pictet and W. Boux. Moll. Foss. Ores verts de 



Geneve, p. 496, pi. xli, fig. 3. 



1854. Gervillia anceps, J. Morris. Cat. Brit. Foss., ed. ii, p. 167. 



— Avicula lanceolata, Morris. Ibid., p. 163. 



1858. Gervilia anceps, F. J. Pictet and E. Benevier. Foss. Terr. Aptien (Matur. 



Pal. Suisse, ser.l), p. 121, 

 pi. xvii. 

 1865. H. Coquand. Mon. Aptien de l'Espagne, p. 145. 



1869. alpina, F.J. Pictet and G. Campiche. Foss. Terr. Cret. Ste. Croix 



(Matur. Pal. Suisse, ser. 5), 

 p. 83, pi. civ, figs. 2—4. 

 1902. Gervilleia anceps, F. Freeh. Centralb. fur Min.,etc, p. 612 (text-figure). 



Description. — Shell elongate, very oblique, slightly inequivalve, the left valve 

 rather more convex than the right. Posterior extremity lanceolate, but rounded. 

 Postero-dorsal margin slightly sinuous. Antero-ventral marginal parts nearly per- 

 pendicular to the plane between the valves and slightly concave. Umbones incon- 

 spicuous, almost terminal. Only a very small portion of the valve is seen in front 

 of each umbo ; on the left valve this portion is bounded by a linear depression, but 

 on the right valve it is not limited. The median part of each valve is convex, but 

 becomes compressed towards the posterior extremity. Between the convex portion 

 and the hinge-line (posterior to the umbo) is a long, triangular, compressed, wing- 

 like portion, of which the inner boundary is not limited, and the posterior margin 



