4i 8 NORTH AMERICAN INDEX FOSSILS. 



Fig. 542. Barbatia micronema, right valves. (U. S. G. S., Bull. 106.) 



XLIV. Glycimeris Da Costa. (Pectunculus Lamarck.) 

 Shell thick, equivalve, suborbicular, almost equilateral. Umbos 

 central, slightly curved posteriorly, separated by a small triangular 

 area provided with diverging grooves for the ligament. Hinge 

 with an arched row of strong, transverse teeth, obliterated at the 

 center in older forms by the growth of the area. Margins of 

 valves crenulate inside. Adductor scars subequal. Pallial line 

 with a very small sinus. Cretacic— Recent. 



149. G. (Axinea)subaustralis(d'Orbigny). (Fig. 543.) Cretacic. 

 Subcircular, very slightly oblique. Beaks strongly elevated 



Fig. 543. Glycimeris (Axinea) subaustralis. (N. J. Pal., I.) 



and pointed. Surface covered with concentric growth lines and 

 fine radiating costae. 



Ripleyan of New Jersey (Merchantville-Tinton), Gulf states. 



