EXPLANATION OF PLATE L. 



Pecten conraui ( W'hiifield ) p. 474 



1-3. Views of the internal casts of three single valves. 



4. The internal cast of one valve and the hnpression of the 



exterior of anejther. 



ll'oodbiii-y clay; LoriUard, (loz). 



Pecten iwrvus (Whitfield) p. 477 



5. View of the type specimen, (x2). 



6. View of the surface markings, (much enlarged). 



Navcsink mail; Frcctiold. 



Pecten cLiFFwonDEXsis n. sp p. 469 



7-8. Views of tWLi internal casts of single valves. The type 

 specimens. 



Cliff iK'ood clay; Cliff wood Point. (105). 



Pecten tenuitestus Gabb, p. 467 



9. View of a squeeze taken from a natural mould of the 

 exterior. 



Xaz'csiiilc marl; near Waliiford, (149). 



Pecten quinquenaria Conrad, I', 476 



10-12. Vie\\s of three imperfect internal casts of separate valves. 

 IJ'cjionaJi sand: near Marlboro, (/Jo). 



13. A nearly complete individual ])reserviiig the shell, from near 



Dumas, Mississiiipi. (Coll. U. S. Nat. Mus , No. 20723,) 



Pecten whiteieedi n. sp., p. 468 



14. View of the type specimen, figured by AVhittield as P. tenui- 



testus Gabb. 



Nai'csiiik' mail; Ilolmdcl. 



P-.CTEN CRATicuEus Morton p. 478 



15-16. Two views of the type specimen. (After Whitfield.) 



hhwesDil; marl; .-Irneylown. 



982 



