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IO75 



TERTIARY FAUNA OF FLORIDA 



Ilcmicardium Swainson, Mai., p. 373, 1840; Roemer, Conch. Cab., 2d ed., p. 100, 1869: 



Cuvier, Regne An., ii., p. 479, 1817, ex parte. 



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

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



Shell subtruncate behind, inflated, with strong ribs, no lunule 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, unedo 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 ; 

 shell colorless, periostracum smooth. Type Cardium graniferuni Sowerby. 



* 



Section Ctenocardia H. and A. Adams. 



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

 p. 1139, 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. 

 Pa/yyridca Swainson, Mai., p. 374, 1840 (C. solcniformc Brug. = C. sfinosum Meuschen). 



Valves elongate oval, gaping, with numerous narrow ribs mote 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. 



