EXPLANATION OF PLATE XIA'lL 



ExoGYRA costata Say p. 45'J 



1. View of n nearly perfect \al\c. 



A'az'csiuk iiiarl : CrfssiL'tiks Creek, {ij6'). 



ExoGYEA PONUEROSA Riienicr p. 458 



2. View of a nearly perfect vahe. 



l\Iarslnilltozcu ilay-iiiurl : near Sivcjcsburo, (i"). 



ExOGYRA sp p. 460 



3. View of an internal cast of a lower valve. 



Mcriliaiitz'illc clay-marl ; I.ciiola, (i6j}. 



OstrEa congi{sta Con p. 435 



4. Vie\v of the internal cast of an attached valve. 



Cliff-a'and clay; Cliffwood Point. {103). 



976 



