EXPLANATION OF PLATE LL 



PectBn vEnustus Mc.irton p. 47S 



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

 single valve, (x2,). 



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



Tintoii bi\ls: Ttiilon falls, (jio). 



4. An internal cast of a single \'alve. 



Red Bank sand; Red Bank, (116). 



5. An internal cast illustrated by Whitfield. 



Nai'csiiik marl. 



Pecten simplicil's Conrad, p. 480 



6. An internal cast of a single valve. 



Tintcni beds: Beers Hill Cut, iuc/'). 



Neithea nuiNouECOST.\TA ( Sowerliy ) p, 481 



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

 trated by Whitfield. 



IJ^cnonah sand. 

 9-10. Two convex valves preser\"ing the shell. 



Ularsliallli'zen eldy-ina)-l ; near S'eedesbfiro, (//"). 

 11-12. LIpper and lower \iews of a nearly complete internal east. 

 Merehautinlle elay-niarl; Lenola, {163). 



984 



