TRANSACTIONS OF WAGNER 

 1008 



TERTIARY FAUNA OF FLORIDA 



The specimens are silicious pseudomorphs and may be defective, yet, ex- 

 cept in respect of the almost microscopic pustules on the grooves of the 

 posterior area, it seems to have all the characteristics of Dinocardium. 



Cardium (Cerastoderma) chipolanum n. sp. 

 PLATE 40, FIGURE 8. 



Oligocene of Alum Bluff and the Chipola beds of the Chipola River, 

 Florida, Burns ; and of Roberts, Escambia County, Alabama, E. A. Smith. 



Shell thin, polished, with large, full beaks ; subequilateral, rounded in 

 front and below, obliquely subtruncate behind ; sculptured with about twenty- 

 four strong ribs, of which the anterior five or six are smooth, thence to the 

 middle of the shell with thickened adherent scale-like ornaments (which I 

 call lepidote for short) especially near the margin, the remainder of the ribs 

 smooth, except on their sides, where they are cross-striated, as are the narrow 

 channelled interspaces ; posterior area smooth with obsolete radial grooves, 

 one or two near the hinge stronger ; no pseudolunule ; hinge normal, strong ; 

 internal margins sharply fluted, sulci reaching well up on the disk. Lon. 34, 

 alt. 36, diam. 24 mm. 



This shell in its general characters is a miniature Cardium robustum, and 

 is especially characteristic of the Chipola horizon. 



Oardium (Cerastoderma) taphrium n. sp. 

 PLATE 40, FIGURE 9. 



Oligocene of the Ballast Point silex beds, Tampa Bay (?), and of the 

 Oak Grove sands, Santa Rosa County, Florida ; Ball and Burns. 



This at first sight might be taken for the preceding species, but an exam- 

 ination shows that the ribs are one-third more numerous, being usually thirty- 

 three or thirty- four; there is a rather large pseudolunule, the shell is pro- 

 portionately more produced behind and below and actually larger when 

 mature. The specimen figured is 35 mm. long, but a full-grown one, obtained 

 later, measures Ion. 48, alt. 47, diam. 34 mm. 



The radial grooves on the posterior area are usually sharper and stronger 

 than in the preceding species. The types come from Oak Grove, where the 

 shell seems characteristic of that horizon. A very poor pseudomorph from 

 Ballast Point is temporarily placed here, though probably more perfect speci- 

 mens would show it belonged elsewhere. It has thirty-two ribs and is appar- 

 ently of squarer form than C. taphrium. 



