OSTREA. 



3G9 



163 



Figs. 154-107. — Ostrea vesicularis, Lam. Zone of Belemnitella mucronata, Norwich. Sedgwick Museum, 

 Cambridge; except 156, 157, in Dr. Eowe's collection. 154, 156, 159, 161, 163, 164, 166, left 

 valves. 155, right valve of 154. 157, right valve of 156. 158, interior of a right valve 

 similar to 157. 160, right valve of 159. 162, right valve of 161. 165, right valve of 164. 

 167, dorsal view of 160. 166 and 167, natural size. Other figures x |-. 



