EXPLANATKJN OF PLATE XLVL 



Gryphaea mutabilis Morton, p. 452 



I. External \iew oi a nearly eoniplete valve. 



!\IarsIiaIllu-H'ii chiy'inarl: near Si^'i'dcsboro, (iSo). 



Gryi'Iiaea nissriiiLAKis n. sp p. 453 



3-4. Two views of a nearly complete indi\'idual retaining" both 

 vahes, 



Honicrston'ii fnai'l ; near JJ'ehMlstozini . (jSl). 



974 



