PELECYPODA—TELEODESMACEA. 



559 



Cretacic. 



plications are preserved an angular appearance is given to the 

 posterior umbonal slope by the greater elevation of three or four 

 of the plications there. 



Coloradoan : Wyoming, Utah, Colorado, New Mexico. 



544. C. speciosum Meek and Hayden. 

 Subcircular, with height slightly ex- 

 ceeding length. Beaks almost central. 

 Surface marked with numerous, very 

 regular, radiating ribs ; in the grooves 

 between these are regularly arranged 

 series of small tubercles. Average diam- 

 eter slightly over .5 inch. 



Montanan : Colorado, Montana. 



545. C. tenuistriatum (Whitfield). (Figs. 766 ; 767.) Cretacic. 



Internal molds strongly gibbous and with abrupt posterior slope. 



Ripleyan of New Jersey (Merchantville-Navesink; the most com- 

 mon and widely distributed Cardium of the New Jersey Cretacic). 



Fig. 765. Cardium pauper- 

 culum, right valve enlarged. 

 (After Stanton.) 



FiCx. 766. Cardium tenuistriatum. (N. J. Pal., I.) 



546. C. eufaulensis Conrad. Cretacic. 

 Height exceeding length ; hinge arcuate ; shell narrower than 



preceding with stronger angular costae (35-40). 

 Ripleyan of New Jersey (Wenonah)-Mississippi. 



547. C. spillmani Conrad. Cretacic. 

 Usually occurs as internal molds which are larger than those of 



C. kummeli, with more anteriorly curved beaks, and with radiat- 

 ing ribs on posterior portion. 



New Jersey (Merchantville and Navesink)-Texas and Ok- 

 lahoma. 



