PLATE LXI. 



Osteea {continued). 

 Figs. 

 1 — 6. 0. lunata, Nilss. Zone of 0. lunata, Trimingham. 1, 5, 6, Mr. R. M. 

 Brydone's Collection. 2 — 4, Sedgwick Museum, la, 2 — 5a, 6a, 

 left valves, lb, right valve of la; \c, anterior view of la. bb, 

 right valve of 5a. 6b, anterior view of 6a. (P. 393.) 



Genus — Exogyra, Say. 



7 — 11. E. tubercidifcra, Koch and Dank. Lower G-reensand. (P. -104.) 



7. Crackers, Atherfield. British Museum, No. L6461. a, right valve; b, left 



valve. 



8. Perna-hed, East Shalford. Sedgwick Museum. Left valve. 



9—11. Hythe Beds, Lympne. Museum of Practical Geology, Nos. 25957, 25958, 

 25968. Left valves. 11a, interior of 11&. 



12. E. sigmoidea, Renss. Zone of Micraster cor-anguinum, Boxford. Mr. 



LI. Treacher's Collection. Right valve. (P. 419.) 



13. E. sinuata (Sow.). Perna-hed, Atherfield. British Museum, No. L 6306. 



Left valve. Variety of the laevigata form with ribs. (P. 395.) 



Supplementary figures. 



14 — 17. Grenella orbicularis (Sow.). Upper Greensand (zone of Schloenbachia 

 rostrata), Blackdown. Sedgwick Museum. 14, 16, right valves. 

 15, 17a, left valves. 17b, dorsal view of 17a. x 2. (P. 423.) 



18. Peeten {Chi amy s) britannicus, Woods. Zone of Micraster cor-anguinum, 



Bromley. Sedgwick Museum, a, right valve ; b, portion above the 

 middle of the valve x 5. (P. 424.) 



19. Lima {Limea ?) sp. Speeton Clay, Speeton. Sedgwick Museum, a, 



right valve ; b, portion x 6. (P. 425.) 



20, 21. Crassatellites ? equisulcatiis (Woods). Chalk Rock, Cuckhamsley. Sedg- 

 wick Museum. 20, left valve; 21, internal cast of right valve. 

 (P. 426.) 



