384 



CRETACEOUS LAMELL1BRANCHIA. 



T 'vS^^Wfaj> 





n 





1 P 



191 



192 



Figs. 183 — 192. — Ostrea semiplana, Sowerby. 183 — 190, Zone of Belemnitella mucronata, Norwich. 

 183 — 185, right valve, and interior and exterior of left valve of one individual; Norwich Museum. 

 186, 187, left and right valves of one individual ; Sedgwick Museum. 188, left valve (the right 

 valve is concave) ; Sedgwick Museum. 189, 190, left and right valves of one individual; Norwich 

 Museum, No. 2101. 191, 192. Zone of Actinocamax quadratus, East Harnham. Dr. Blackmore's 

 Collection. Exterior and interior of a right valve. All x i. 



