558 NORTH AMERICAN INDEX FOSSILS. 



Common in the Chickasawan (Lignitic) of Atlantic and Gulf 

 region. 



541. D. acclinis Conrad. (Fig. 763, a, b.) 



Miocenic and Pliocenic. 

 More transverse. Growth lines strong. 



Characteristic of the Miocenic of New Jersey-North Carolina. 

 Pliocenic : South Carolina and Florida. 



CLVI. Tenea Conrad. 

 Subcircular, thin-shelled, tumid. Left valve with V-shaped 

 cardinal tooth, the anterior lobe of which is continued along the 

 anterior margin of the shell and separated from it by a deep groove. 

 Right valve with two cardinal teeth, the anterior falcate, the pos- 

 terior curved backwards. No laterals present. Valve margins 

 smooth. Pallial line with a narrow and deep sinus. Cretacic. 



542. T. parilis Conrad. (Fig. 764.) Cretacic. 



Fig. 764. Tenea parilis. (N. J. Pal., I 



Surface nearly smooth, marked only by fine growth lines. At 

 times 1.5 inches in diameter. 



Widely distributed through the upper Cretacic of New Jersey, 

 also in North Carolina and Gulf region. 



CLVII. Cardium Linne. 



Convex, nearly equilateral, rounded-oval. Umbones prominent, 

 incurved, turned slightly forward. Surface marked with radiating, 

 often spiny ribs. Margins of valves crenulated. Two cardinal 

 teeth, one anterior lateral and one posterior in each valve. No 

 lunule nor escutcheon present. Ligament external. Adductor 

 impressions shallow. Triassic-Recent. 

 543. C. pauperculum Meek. (Fig. 765.) Cretacic. 



Height slightly exceeding length. Diameter .5 to .75 inch. 

 Specimens are usually flattened or otherwise distorted. When the 



