APPENDIX I. 



NORTH AMERICAN TERTIARY OSTREID^. 



By Prof. Angelo Heilpkin. 



Genus Ostrea Linnaeus. 



EOCENE. 



Ostrea alabamensis Lea. 



(Plate LXIV, Figs. 2, 3, 4.) 



Originally published from Alabama in Lea's Contributions to Geology, 

 page 91, Plate III, Fig. 71. 



Syn. — 0. Zini/Ma-canis Lea. lb., page 92. 

 0. pincerna Lea. lb., page 92. 

 *0. aemilunata Lea. lb., page 90. 



Ostrea carolinensis Conrad. 



From South Carolina. Published in Conrad's Fossil Shells of the 

 Tertiary Formation, first edition, page 27, Plate 14, Fig. 1. 



Ostrea compressirostra Say. 



(Plate LXV, Figs. 1, 2.) 



Published from Maryland, in the Journal of the Philadelphia Academy 

 of Natural Sciences, IV, page 132. 



Syn.— 0. helloracina Conrad ; ProceediDgs of the National Institute, page 172. 



It appears to me very doubtful whether the character of the beaks 

 pointed out by Say (Journal of the Academy of Natural Sciences, IV, 

 page 133) to distinguish this species from the 0. bellovacina Lamarck, is 

 a constant one or not, and I have therefore some hesitation in recogniz- 

 ing it as a distinct species. The beaks of 0. compressirostra certainly do 

 appear more compressed than thej- are shown to be in the majority of 

 figures representing the European oyster ; but at least someof the speci- 

 mens in the collection of the Philadelphia Academy of Natural Sciences 

 of 0. bellovacina (var. edulina) from the London Clay of Bognor, have 

 the beak undistinguishable from those of the American species. 



The want of specimens with which to make the proper comparisons, 

 and the difiBculties that attach to the definition of the specific charac- 



* This last form is very distinct from the 0. seUwforviis of Conrad, which is noticed on 

 a following page. 



309 



