EXPLAXATluN OF PLATE LXVIII. 



IMerKThix TirPAXA Cunrail, p' 607 



1-2. Internal and (.-xtcrnal views of a perfect left \'alve. 



Rit-li-y, Miss. Coll. U. S. Nat. I\Ius., No. 20,690. 

 3. A somewhat ilistorlej cast of the interior of a left valve. 

 Mcrchaiili-illc clay-marl ; I.ciiola, f/6_?). 



MfiRETRix CRiiTACEA ( Conrad ) , p. 608 



4-5. Views of two right \'alves. 



6-7. Views of tlie hinges of the two valves. 



iMursluilUoivn clay-marl; near Sivcdcsboro, (177). 



MerEtri-X Eue.vulExsis ( Conrad), p. 609 



8. View of a left vahe. 

 9-10. Interior and exterior views of a left valve. 



Illarshalllozun clay-marl; near .Siacdcsboro, {177). 



Cary.vtis vETa Whitfield, p. 611 



11-12. Anterior and lateral \"iews of an intern.al cast. 



ilaiiasqiiaii marl; near A'cia Egypt, (155). 



Petricola NOVA-AEGvriiCA AAdiitheld, p. 614 



13. Lateral \iew of the type specimen. 



Manasqnan marl; near Xcia Egypt. 



Cyprimeria densat.v ( Conrad ) p. 601 



14. Lateral view of a large internal cast of a left valve. 



A\rz'csink jnarl; Ilolmdcl. 



1018 



