OSTREA. 



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Ficis. lol-ltu .—Os/rea vesicularis, Lam. Zone of Be!enini<e/(rt nii(ci-oiia(a, Norwich. St-dgwick Museum. 

 Cauiliiidfje ; except 15G, 157, in Dr. Kowe's collection. 1.54, 156, 159, 161, lO:!, Kit, 166, left 

 valves. ° 155, right valve of 154. 157, right valve of 1.56. 158, interior of a right valve 

 similar to 157. " IW", right valve of 15'J. 162, right valve of 161. 165, right valve of 164. 

 167, dorsal view of 166. 166 and 167, natural size. Other figures x J. 



