367 



Figs. 143-153. — Ostrea vesicularis, Lam. 143-145. Upper Greensand (zone of P. asper), Warminster. 

 Museum of Practical Geology, Nos. 25948, 25950. 143, left valve. 144, right valve. 145, anterior 

 view of 144 showing both valves. 146. Zone of Micraster cor-anguinum, Witherington, Dr. 

 Blackmore's Collection. Interior of left valve. 147. Zone of Actinocamax quadratus, East 

 Harnham. Same Collection. Right' valve. The left valve is entirely attached to the convex 

 surface of an echinoid. 148, 149. Zone of Micraster cor-anguinum, Gravesend. British Museum, 

 No. L. 20991. Exterior and interior of a left valve. 150-153. Zone of Belemnitella mncronata, 

 Norwich. 150, right valve, British Museum, No. L. 20616. 151, Dorsal view of 150 showing both 

 valves ; the left valve entirely attached to a nearly flat surface. 152, 153. Sedgwick Museum. 

 Left and right valves. 146, 147, natural size. Other figures x £. 



