LAMELLIBRANCHIATA. 



FAMILY OSTREDXE. 



Genus GRYPH^EA, Lamarck, 1801. 



GRYPH2EA 



PI. 8, Pig. 4, and 4 a. 



Shell thin, rather under medium size, varying from subovate 

 to suborbicular. Under valve moderately deep, generally more 

 or less lobed on the anterior side ; beak not prominent, scarcely 

 rising above the hinge. Upper valve flat, or slightly concave; 

 beak not truncated. Surface of both valves apparently with only 

 moderately distinct concentric marks of growth. 



Length, about 1.68 inch ; breadth generally less ; convexity, 

 about 0.45 inch. 



The specimens of this Gryphcea, in the collection, are too imperfect to admit of 

 a sufficiently satisfactory comparison with known species to determine whether or 

 not it is new. So far as can be made out, from the imperfect specimens at hand, 

 it seems to present somewhat the form of G. vesicularis; but is considerably smaller 

 than the average size of that species, and more narrowed towards the beaks. It 

 also differs in having the beak of the upper valve not truncated, but angular and 

 curved a little to the left side. It seems to be more nearly allied to some Jurassic 

 forms than to G. vesicularis. 



(42) 



