PLATE XI. 



Gervillia (continued). 



Figs. 

 1. G. sublanceolata (d'Orb). Upper Greensand, Blackdown. Sedgwick 

 Museum. Interior of part of a right valve. (P. 74.) 



2 — 8. G. liTiguloides, Forbes. Lower Greensand (Crackers), Atherfield. 

 Figs. 2—4, 6—8, Sedgwick Museum; fig. 5, York Museum. (P.78.) 



2. Left valve x U. 



3. Hinge of left valve x 3. 



4. Right valve x H. 



5. Left valve x If. 

 6 — 8. Left valves. 



9 — 11. G. alatformis (Sow.). Lower Greensand (Crackers), Atherfield. Sedg- 

 wick Museum. Figs. 9, 10, young specimens. (P. 79.) 



9 a, left valve ; b, portion near umbo x 3 ; c, right valve ; d, dorsal view. 

 10 a, left valve x 1| ; b, ribs near the middle of the left valve x 3 ; c, hinge of 



same valve x 3 ; d, area and ligament pits of right valve of the same 



specimen x 3. 

 11. Hinge of adult specimen. Perna-hed, Atherfield. 



12 — 23. G.rostrata (Sow.). Upper Greensand, Blackdown. 12 — 19, left valves. 

 20—22, right valves. Sedgwick Museum, except figs. 13, 15, 22, 23. 

 (P. 83.) 



12 b, interior of 12 a, x U. 



13. Museum of Practical Geology, No. 10784. 



15. British Museum, No. L, 16872. 



19. Hinge x 2. 



22. Haldon. Museum of Practical Geology, No. 10783. 



23. Dorsal view of the Type. Bristol Museum. 



24, 25. G., sp. Lower Greensand (Ferruginous Sands), Shanklin. Sedgwick 

 Museum. Left valves. 24 x 1£. (P. 85.) 



2(5, 27. G. Forbesiana, d'Orb. Right valves. Sedgwick Museum. (P. 85.) 



26. Lower Greensand (Crackers), Atherfield. 



27. Gault, Folkestone. 



