TERTIARY AND QUATERNARY PALEONTOLOGY, NORTHEASTERN FLORIDA 47 
Cotypes (Cat. No. U. S. N. M. 352276, spec. A; 352277, spec. B). 
These measure: length,—specimen A, 2.5; specimen B, 2.3 mm.; 
diameter of aperture,—specimen A, .6; specimen B, .7 mm.; diameter 
posterior end,—specimen A, .5; specimen B, .5 mm. 
Geologic horizon: Upper Pliocene or lower Pleistocene. 
Type locality: One-half mile above A. C. L. R. R. bridge over St. 
Johns River, Putnam Co., Fla., five feet above high-water level and 
seven feet below surface. F. G. Clapp, collector, U. S. Geol. Surv., Sta. 
No. 6096. 
Discussion: This species somewhat resembles Caecum carolinia- 
num Dali, but differs from the latter in having an anterior ring, a 
more rounded plug, and lacking longitudinal sculptured striae. It is 
closely related to Caecum chipolanum Gardner (an unpublished Ms.) 
species from the Chipola marl member of the Alum Bluff formation, but 
the latter possesses an anterior furrow and is a much heavier and more 
tapering shell. 
cardita (carditamera) OSCEOLAENSIS n. sp. 
Plate I, Figures 11 and 12. 
Shell very thin, small, ovate; beaks not prominent, slightly twisted 
forward, situated at the anterior third of the valves; lunule long, moder¬ 
ately impressed; anterior side and middle of valves rounded; posterior 
side steeply sloping; posterior dorsal margin nearly straight, sloping 
at a low angle; anterior dorsal margin sloping and slightly undulated; 
posterior margin nearly straight, truncating the end, making nearly a 
right-angle with the dorsal margin and a rounded edge with the ventral; 
anterior margin rounded; ventral margin arcuate. Shell. sculptured 
radially by 20, rather low, rounded ribs, nodulous about the beaks and 
roughened distally by transverse ridges or imbricated growth lines. 
Whole surface sculptured radially by fine, indistinct lines and transverse¬ 
ly by rather fine imbricated growth structure. Inter-radial spaces about 
one and one-half as wide as ribs on the anterior and center of the disk, but 
narrower at posterior angle where ribs widen out. Lateral teeth small; 
anterior cardinal slender and prominent. Interior surface markedly 
fluted, reversing external sculpture and showing a pecten-like appear¬ 
ance. 
