FREE INSTITUTE OF SCIENCE 



1075 



TERTIARY FAUNA OF FLORIDA 



Hemicardium Swainson, Mai., p. 373, 1840; Roemer, Conch. Cab., 2d ed., p. 100, i86g; 



Cuvier, Regne An., ii., p. 479, 1817, ex (lartc. 

 Bucardium Gray, Ann. Mag. Nat. Hist., 1853, p. 40; not of Megerle, Entw., p. 52, 1811. 

 Loxocardiuni Cossmann, Cat. Illustr.. p. 160, 1887. 



Shell subtnincate behind, inflated, with strong ribs, no lunula or escutcheon, 

 the channels simple, hinge normal, pallial line nearer the basal margin than in 

 most Cardia. 



Section Fragum s.s. 

 Valves obtusely angular in front of the truncation, ribs numerous, strong, 

 pustular, or imbricate throughout. Type C. uncdo L. 



Section Hemicardium (Cuvier em.) Dall. 

 Valves more or less keeled behind the truncation, ribs comparatively few, 

 low, flattish, only those near the middle of the shell pustular ; channels con- 

 centrically sculptured. Type C. hemicardium L. 



Section Trigoniocardia Dall. 

 Shell small, few ribbed, medial ribs very strong; posterior end subtrun- 

 cate with smaller closer ribs ; channels strongly concentrically sculptured ; 

 sliell colorless, periostracum smooth. Type Cardium graniferum Sowerby. 



Section Cieiwcardia H. and A. Adams. 

 Ctenocardia H. and A. Adams, Gen. Rec. Moll., ii., p. 459, 1857; Fischer, Man. Conch., 

 p. 1 139, 1887. Type C. hystrix Reeve. 



Like Fragum s. s., but the ribs profusely spinose, the truncated area desti- 

 tute of spines, or with much smaller ones. 



Subgenus PAPYRIDEA Swainson. 



Papyridea Swainson, Ma!., p. 374, 1840 (C. soleniforme Brug. =: C. spiiwsuiu Meuschen). 

 Valves elongate oval, gaping, with numerous narrow ribs more or less 

 tuberculose or spiny. 



Section Papyridea s.s. 

 Shell thin, gaping at both ends, subcompressed, the posterior margin around 

 the gape deeply serrate ; periostracum inconspicuous. 



