PLATE XX. 



Cyprtna (ronthiv/'tJ). 



Figs. 



1-5. G. Srclgioiclci (Walker). Lower Greensand. (P. 133.) 



1. Potton. The Type. Mr. Walker's Collection, a, right valve; h, dorsal view of 

 both valves. 

 2-5. Upware. Sedgwick Museum. 2, 4, 5, left valves. 3 a, right valve ; 3 h, anterior 

 view of 3«. 



G. C. (Mum, Keeping. Lower Greeiis^aiid, Upwarc. Sedgwick iMuseuiii. 

 The Type, a, left valve ; h, dorsal view. (P. 133.) 



7-12. G. niDonta, Sow. Upper Greensand, Blackdown. (P. 13 1-.) 



7. British Museum, L 170G6. Eight valve. 



8. British Museum, L 17066. Left valve. 



9, 10. Sedgwick Museum. Left valves. 10 h, dorsal view of 10 k. 

 11. British Museum, L 1706G. Left valve. 

 12 a. British Museum, L 17066. Eight valve. 12 6, hinge, x \\. 



13. G. tenlhienniii. Woods. Tealby Limestone, Claxby. British Museum, No. 



49985. <i, left valve, X f ; h, ilorsal view of both valves, X f . 

 (P. 130). 



14. G. sp. Speeton Clay, Specton. Sedgwick Museum. Left valve. (1'. 



137.) 



15,10. G. oiu/lic(i, Woods. Lower Greensand (Crackers), AtluMficld. Sedg- 

 wick Museum. Left valves. (1'. 137.) 



