FREE INSTITUTE OF SCIENCE 



1073 



TERTIARY FAUNA OF FLORIDA 



geniculate, smooth, the pallial line rather distant from the margin of the 

 valves. Hmge r, ioLi^io. loi " 



Subgenus CARDIUM s.s. 



Shell rotund, closed, with spinose ribs and granulose or cross-striated 

 channels ; left cardinals anterior when interlocked. 



Subgenus TRACHYCARDIUM Morch. 



Trachycardium Morch, Yoldi Cat., ii., p. 34, 1853 (C. isocardia L.). 

 Granocardium Gabb, Pal. Cala., ii., p. 266, 1868 (C. sahulosum Gabb). 



Shell like Cardiuin s. s., but with the ribs imbricate or granulose ; the 

 channels also sometimes granulose. 



Section Acrosterigma Dall, 1900. 

 Shell with an elevated mesial rib internally, radiating from the umbonal 

 cavity. Type Cardium Dalli Heilprin. 



Subgenus RINGICARDIUM Fisher. 



Ringicardium Fischer, Man. Conch., p. 1037, 1887 (C. ringens Gmelin). 



Bucardium Gray, Ann. Mag. N. Hist., 1853, p. 40 {ex parte, not of Megerle, Entw., p. 52, 



1811). 

 Pectunculus (Adanson) Morch, Yoldi Cat., ii., p. 33, 1853 (not of Lamarck, 1799). 



Shell rotund, gaping, with flat ribs and channels, the posterior area with 

 granulose channels ; posterior margin sharply spinose, the spines crossing 

 each other over the gape ; left cardinals when interlocked posterior to the 

 right ones. 



Subgenus CERASTODERMA Morch. 



Cerastoderma Morch, Cat. Yoldi, ii., p. 34, 1853: Roemer, Conch. Cab., 2d ed. (Cardium), 



p. 40, 1868; Meek, Pal. Upper Missouri, p. 166, 1876; C. edule L. 

 Cardiuin Gray, List Brit. An., p. 25, 1851 ; not of Lamarck. 

 Parmeardiuin Monterosato, Sin. Conch. Medit., p. 19, 1884. 



Shell rotund or obovate, closed ; with strong ribs obsoletely granulose or 

 imbricate or smooth ; no posterior or anterior area, channels simple ; hinge 

 normal. 



