402 FOSSIL OSTREID^ OF NORTH AMERICA. 



PLATE LXVIII. 

 OSTKEA SUBFALCATA Conrad. (Page 313 ) 



Fig. 1. — Upper view; natural size. 



a, 3. — Exterior and interior views of an under valve. 



OSTREA ATTWOODI Gabl). (Pages 312 and 314.) 



4. — Exterior view of an under valve.' 



5. — Interior view of another under valve. After Gabb. 



