TRANSACTIONS OF WAGNER 

 1074 



TERTIARY FAUNA OF FLORIDA 



Section Cerastoderma s. s. 



Shell white, with coarse or tufted periostracum, the ribs similar, and usu- 

 ally obscurely nodulose ; inhabiting boreal seas or comparatively deep water. 



Section Dinocardiuni Dall, 1900. 



Shell with more or less coloration, periostracum thin, polished, and incon- 

 spicuous ; ribs with, anteriorly, arcuate hardly raised imbrications ; mesially, 

 flattened and nearlj' smooth ; posteriorly, depressed and polished. Type Car- 

 diuin magnum Born, =^ C. ventricosunt Brug. 



This group is notable for its elegant sculpture, from which spines, pustules, 

 and elevated scales are absent. It replaces in warmer waters of America the 

 Cerastodermas of the North, and goes back in geological time, with its 

 characters well marked, as far as the Oligocene. 



Subgenus ETHMOCARDIUM White. 



Ethmocardium White, Proc. U. S. Nat. Mus., ii., p. 291, 1880. Type Cardium spcciosuui 

 Meelt and Hayden, Proc. Acad. Nat. Sci. Phila. for 1856, p. 274, 1857 ; not Cardium 

 speciosum Adams and Reeve, Voy. Samarang, p. yy, pi. 22, fig, 9, 1850. 



Shell ovate, closed, usually with plain ribs and channels, internally with 

 the pallial area deeply pitted in lines corresponding to the external channels, 

 the pits nearly reaching the external surface. 



This type is believed to be characteristic of the Upper Cretaceous. The 

 specific name of the typical species is preoccupied and I would propose for it 

 the new name of Cardium (Ethmocardium) Whitei. 



Subgenus TROPIDOCARDIUM Roemer. 



Tropidocardium Roemer, Conch. Cab., 2d ed. {Cardium), p. 13, 1869 (C costatum L.) ; 

 Meek, Pal. Upper Missouri, p. 166, 1876. 



Shell with a straight hinge-line, subauriculate, inflated, rotund, gaping 

 behind, with ribs bearing hollow keels or spines ; interior with excavated 

 radial channels behind the middle line; hinge normal. 



Subgenus FRAGUM Bolten. 



Fraguin Bolten, Mus. Boltenianum, p. 189, 1798; ed. ii., p. 131, 1819 (C. iinedo L.) ; 



Morch, Cat. Yoldi, ii., p. 35, 1853. 

 Isocardia Oken, Lehrb. Naturg., pp. viii., 234, 1815 {ex parte, not of Lamarck, 1799). 



