TRANSACTIONS OF WAGNER 

 1086 



TERTIARY FAUNA OF FLORIDA 



(Group of C. muricatum Linne.) 

 Cardium (Trachycardium) precursor n. sp. 



PLATE 48, FIGURE 10. 



Oligocene of Vicksburg, Mississippi ; L. C. Johnson. 



Shell small, moderately inflated, rather thin, nearly equilateral, the beaks 

 small and slightly prosogyrate; sculpture of thirty-seven to thirty-eight 

 strong, well-defined ribs, mostly of triangular section, with narrower chan- 

 nelled interspaces; the ribs on the anterior face minutely nodulous, the pos- 

 terior ten flattened and more or less spinose with minute prickles ; the whole 

 shell finely concentrically striated, so that in perfect specimens the summit 

 of the ribs on the disk is probably minutely crenate ; internal margin sharply 

 fluted ; hinge normal, strong. Alt. 22.5, Ion. 22, diam. 14.5 mm. 



The single valve of this species in the National Collection appears dis- 

 tinct from any of those heretofore described from the Vicksburgian, and by 

 its sculpture foreshadows the type to become so well-developed. 



Cardium (Trachycardium) virile n. sp. 

 PLATE 48, FIGURE I. 



Oligocene of the Chipola marl, Calhoun County, Florida ; Dall and Burns. 



Shell small, solid, strong, rounded, subovate, with about thirty-eight rather 

 close-set ribs, with narrower channelled interspaces; the anterior ribs to the 

 number of about fourteen exhibit the strung and flattened cup-imbrication 

 like Cardium consors in miniature; the posterior fourteen are asymmetrical, 

 with an undulate or irregularly twisted serrate keel on the anterior side of the 

 rib ; those in the middle of the disk have a similar keel on the posterior side 

 of the rib ; the outer posterior ribs are more or less muricate or spinulose, 

 and the posterior margin is serrate, the rest merely fluted internally ; excep- 

 tionally perfect small specimens show small and extremely delicate spines on 

 the medial ribs. Alt. 27, Ion. 25.5, diam. 18 mm. 



The delicacy and fragility of the ornamentation of this little shell are such 

 that not a single specimen of many preserved its sculpture intact. 



Cardium (Trachycardium) parile n. sp. 



PLATE 48, FIGURE 17. 



Oligocene of the lower bed at Alum Bluff and on the Chipola River, Cal- 

 houn County, Florida. 



