102 AMERICAN JOURNAL 



lateral tooth in each valve, in the left valve excavated ; poste- 

 rior lateral teeth in the left valve 3, parallel with the cardinal 

 line ; pallial line entire ; anterior side gaping. 



Corhis cordifonnis, D'Orbigny. Cretaceous. 



This genus differs essentially from Corhis, Cuv., in the ar- 

 rangement of the hinge teeth, and is not of earlier date than the 

 Necomian Cretaceous. This fossil is common in Egypt as well 

 as France. 



Whether Corhis rotimdata, D'Orbigny, is a member of this, 

 genus is doubtful, as the hinge character diflfers. 



Triassic. 



SOLEMYA. 



S. TRIASINA, Conrad. 



Description. — Oval, extremely thin ; end margins subequal 

 and obtuse. Length If inch. Height 1 inch. 



Locality. — Near Perkiomen Creek, Penn. 



This cast, with portions of the shell remaining, is in a dark, 

 hard slate colored shale. Traces of the extra marginal perios- 

 traca are seen in plications on the stone. Plications are also 

 visible on the posterior side near the extremity on one valve, and 

 other obtuse folds may be the result of pressure on a very thin 

 shell. 



My apology for describing this obscure cast is that organic re- 

 mains, especially shells, are comparatively few in the Triassic 

 rock of Pennsylvania, and I wish to call attention to this bivalve 

 that better specimens may be searched for by collectors and nat- 

 uralists. 



DONAX, Linn. 

 D. FoRDii, Conrad.— PL 9, fig. 27. 



Description, — Triangular, inequilateral, ventricose ; extremi- 

 ties acutely rounded ; radiated by minute, close impressed lines, 

 near the posterior ventral margin a few concentric lines are Gra- 

 nulated by the junction with the radiating lines. 



iocaZ%.— Haddonfield, N. J. Mr. J. W. Ford. 



ERYCINELLA, Conrad. 

 Woodia Icevigata, Speyer, is a species of this genus. 

 Reference. — Dunker's Palaeont. pi. 30, fig. 8. 



