GERVILLIA. 85 



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

 siglit to be distinct from the more abundant oblicpic forms, but there is a comijlete 

 transition between the extremes. 



Didrihation. — Upper Greensand (zone of Schhciihachia roslrata) of Blackduwn, 

 Haldon, and ? Devizes. ? Upper Gault (zone xi) of Folkestone. 



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



Specimens from the Ferruginous Sands of Shaiiklin, whicli were collected by 

 the late 0. J. A. Meyer aud are now in the Sedgwick Museum, resemble closely 

 G. rostrata and G. tenuicostata (Pictet and Campiche),^ 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 Upware figured l)y Keeping" as 

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

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



Gekvillia Foebesiana, tVOrhigiuj, 184G. Plate XI, figs. 2G, 27. i'late Xli, figs. 1-5. 



1826. Gekvillia solenoides, /. de C. Sowerhy. Mill. Coiicli., vol. vi, p. 1-i, id. dx, 



figs. 1—3 (not 4). 



1845. — — E. Forbes. Quart. Jouru. Geol. Soc, vol. i, \). '2U>. 



1846. — FoBBESiANA, A. cVOrhiijnij. Pal. Trau^. Terr. Crct., vol. iii, p. 



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

 1850. — — d'Orbiynij. I'rodr. de Pal., vol. ii, p. 119. 



1854. — SOLENOIDES, J. Morris. Cat. Brit. Poss., ed. 2, p. 168 (jjarliiii). 



1897. — FoRBESiw A, E. B. Newton. Proc. Dorset. Nat. Hist, aud Antiq. 



Field Club, vol. .wiii, p. 87. 



Descrijjliun. — 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 abruj)tly, but 

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

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

 sti'aight or very slightly concave and its posterior margin curving backwards so as 

 to form an acute angle witii the dorsal margin of the valve. The ear is marked by 

 fine growth-lines parallel with its posterior border. 



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



■ 'Foss. Nooc. Upware aud Brickhill" (1883), p. 109, pi. v, fig. 3. 



