128 Bulletin 4 242 



Explanation of Plate i. 



(II) 



Page. 



Fig. I. Ostrea crenulimarginata Gabb 45, 159. 



Exterior, left valve.* 

 a. Interior, left valve.* 



2. Ostrea pulaskensis Harris 46, 160. 



Exterior, left valve. 



a. Posterior view, left valve. 



b. Exterior, right valve. 



c. Interior, right valve. 



3. Ostrea ptdaskensis Harris. Small variety found imme- 



diately above the Cretaceous-Eocene contact line in 

 the vicinity of Prairie Bluff, Ala. 

 Posterior view, left valve, 

 a. Exterior, left valve. 



Note. — All figures are natural size unless otherwise indicated. 

 Those marked ( * ) in the explanation were drawn by Dr. 

 McConnell of Washington for Mr. Aldrich, and were lent by 

 the latter for use in this publication. Those marked ( f ) were 

 drawn by McConnell and were published elsewhere as shown 

 b}^ the synonym3^ All others were drawn by the author of this 

 Bulletin. 



