EXPLANATION OF PLATE LI. 



PECTEN VENUSTUS Morton, p. 47$ 



1-2. The internal and external surfaces of a natural mould of a 

 single valve, (x2). 



3. The same impression of the exterior, (x6). 



Tinton beds; Tinton Falls, (no). 



4. An internal cast of a single valve. 



Red Bank sand; Red Bank, (116). 



5. An internal cast illustrated by Whitfield. 



Navesink marl. 



PECTEN SIMPUCIUS Conrad, p. 480 



6. An internal cast of a single valve. 



Tinton beds; Beers Hill Cut, (129"). 



NEITHEA QUINQUECOSTATA (Sowerby), p. 481 



7-8. Two views of a large internal cast of the convex valve. Illus- 

 trated by Whitfield. 



Wenonah sand. 

 9-10. Two convex valves preserving the shell. 



Marshalltown clay-marl; near Swedesboro, (.277). 

 11-12. Upper and lower views of a nearly complete internal cast. 

 M erchantville clay-marl; Lenola, (163). 



984 



