PLATE LVII. 



OSTREA [coil tinned). 

 Figs. 



1 — 13. 0. semiplana, Sow. Upper Chalk. (P. 379.) 



1 — 4 Zone of Belemnitella mucronata, Norwich. Norwich Museum, la, 2a, 3a, 

 4a, right valves, lb, 2b, ob, 4b, left valves. 



5. Uintacrinus band, Thanet Coast. Dr. Rowe's Collection, a, left valve ; 



b, interior of the same; c, right valve of the same specimen. 



6. Zone of Behmnitella mucronata, Hartford Bridge, Norwich. Dr. Rowe's 



Collection, a, right valve; b, left valve. 



7. Same zone, Norwich. Norwich Museum, a, left valve ; b, interior of the 



same. 

 8, 9. Uintacrinus band, Thanet coast. Dr. Rowe's Collection. 8, 9a, right 

 valves ; 9b, left valve. 

 10 — 12. Zone of Belemnitella mucronata, Norwich. Sedgwick Museum, Cambridge. 

 10, 11a, 12, right valves; 116, left valve; 126, posterior view of 12a. 

 13. Same zone and locality. Norwich Museum, No. 2130. Risrht valve. 



