GERVILLIA. 85 



and some of the less oblique specimens (Plate XI, figs. 17, 18) appear at first 



sight to bo distinct from the more abundant oblique forms, but there is a complete 

 transition between the extremes. 



Distribution. — Upper Greensand (/one of Schloenbachia rostrata) of Blackdown, 



llaldon, and ? Devizes. ? Upper Gaalt (zone xi) of Folkestone. 



Geevillia, sp. Plate XI, figs. 24, 25. 



Specimens from the Ferruginous Sands of Shanklin, which were collected by 

 the late C. J. A. Meyer and are now in the Sedgwick Museum, resemble closely 

 G. rostrata and G. tenuicostata (Pictet and Campiche), 1 but the material at present 

 available is hardly sufficient to justify a definite conclusion as to their relationship. 

 The specimen from the Lower Greensand of Up ware figured by Keeping 2 as 

 Perna sp. uov. resembles still more closely some examples of G. rostrata ; the 

 original is in the collection of Mr. J. F. Walker. 



Gebvillla. Foebesiana, d'Orbigny, 1846. Plate XI, figs. 26, 27. Plate XII, figs. 1-5. 



182G. Gervillia solenoides, /. de C. Sowerby. Mhi. Coiicli., vol. vi, p. 14, pi. dx. 



figs. 1—3 (not 4). 



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



1846. Foebesiana, A. d'Orbigny. Pal. Franf. Terr. Cn't., vol. iii, p. 



486, pi. cccxcvi, figs. 5, 6. 

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



1854. solenoides, /. Morris. Cat. Brit. Foss., ed. 2, p. 168 (pwrtvm). 



1897. — Fokbesian a, B. B. Newton. Proe. Dorset. Nat. Hist, and Ant i<|. 



Field Club, vol. xviii, p. 87. 



Description. — Shell compressed, slender, greatly elongated, sabre-shaped, taper- 

 ing posteriorly to a rounded or subtruncate extremity. Dorsal margin slightly 

 concave; ventral margin convex, with a rather greater curvature than the dorsal 

 margin. Near the dorsal margin the valves are compressed rather abruptly, I nit 

 vent rally to this they are compressed gradually, giving rise to a knife-like edge. 

 Umbones terminal, acute. Posterior ear large, triangular, with its dorsal margin 

 straight or very slightly concave and its posterior margin curving backwards so as 

 to form an acute angle with the dorsal margin of the valve. The ear is marked In- 

 fine growth-lines parallel Avith its posterior border. 



1 'Terr. Crct. Ste. Croix ' (1869;, p. 88, pi. clvi, figs. 4, 5. 



2 ' Foss. Neoc. Upware and Brickhill ' (1883), p. 109, pi. v, fig. S. 



