LAMELLIBRANCHIATA OF THE LOWER MAELS. 69 



I strongly suspect this to be identical with Avicula laripes Morton, 

 which was from the Cretaceous marls of Delaware, but of which I have 

 not seen specimens. The shell is somewhat more oblique than Morton's 

 figure, and it does not appear to have been extended into the wing-like 

 projection indicated by him. The radii have about the same distance and 

 direction, as far as can be determined fi'om the poorly-preserved cast used, 

 but are not distinct enoiigh to count, so I cannot be certain of its identity. 

 From Pterki linguiformis E. & Shum., found in the Cretaceous beds of the 

 West and in Texas, it differs in being more oblique and more transverse, 

 with a less width of the body of the shell, and the beaks do not appear to 

 have been so strongly elevated above the hinge, and consequently the lig- 

 amental area is much narrower. 



Formation and locality. — The only specimen of the species which I have 

 yet seen is from the ironstone nodules found in the lower clays of the Cre- 

 taceoiTs, at or near Keyport, N. J., and is from the collection of Columbia 

 College, New York. 



Pteria laripes. 

 Plate XIV, Fig. 9. 



Avicula laripes Morton. Synojisis p. 63, PI. XVIF, Fig. .5. Gabb. 

 Pteria laripes (Mort.). Meek, Check-list, p. 9. 



Shell of but moderate size, oblique ovate and moderately convex, with 

 rather prominent beaks. Hinge less than half the length of the body of the 

 shell, forming on the posterior side a proportionally large wing, which is 

 obtusely pointed at the extremity and only shallowly sinuate on the outer 

 margin between the hinge line and body of the shell. Anterior wing 

 unknown. Surface of the shell, on the left valve, strongly marked b}- distant 

 elevated radii, which seem to have been alternately coarse and fine on the 

 posterior half of the valve, judging- from the only cast examined, and equal 

 in strength and moderately curved forward on the anterior half; while the 

 margin of the valve seems to have been marked by strongly projecting 

 points corresponding to the ribs. 



The specimen used in the above description is so nearly like Dr. 

 Morton's figure that were it not a left instead of a riglit valve I should have 

 supposed it to be the same individual. The specimen is a cast in rather hard 



