EXPLANATION OF PLATE XLIIL 



OsTREA DENTicuiji-EKA Conrad, p. 436 



1-2. Lilcrnal and external \'ie\vs of two nearly coniplelc \'alves, 

 identified b\- Conrad. (After W'hitlield. ) 



H'oinlbiiry clay: Haddoii-ficld. (iS^). 



OstkEa rAtCATA i\Iorton p. 444 



3-6. \'iews of fonr nearly perfect sin.yle \alves. 



J\[urshaIlto-wii clay-iiuirl ; near Szi^cdcsboro, (lyy). 



OstrEa xasuta Morton p. 447 



7-8, Views of two nearly eomplete single valves. (After A\'hit- 

 field.) 



Na'^'csink marl. 



Ostrea iiesEnterica Morton p. 446 



9-14. Views of six nearlx' perfcet single valves. 



A'az'csiiilc marl; iicai- llohndcl. (isf"). 



OsTREA MON.MOUl'HEXSIS n. sp, p. 442 



15. View of the type speeimen. 



Navcsiak marl; near Craicfords Corner. (J_'6'). 



Ostrea con^esta Crmrad p. 435 



If). View of an internal cast of the attached valve. 



Cliffzvood clay: Cliftzvood Point, (10;,). 



Ostrea tecticosta Ciabb p. 443 



17-18. Views of two casts of single valves referred to this species. 

 Jl'cnonali sand: near Marlboro, ( Jjjo ) . 

 10. Exterior \-iew oi the l\pe specimen. (After Vdiitlield.) 



968 



