50 PROCEEDINGS OF THE ACADEMY OF [Feb., 



Dentition. — Hinge heavy for the genus and astonishingly variable 

 within the limits of the species. Anterior cardinal of the right 

 valve laminar, almost or entirely obsolete, the posterior trigonal 

 and very strong. Cardinals of the left valve equal size and fairly 

 strong. Laterals heavy, two in number in each valve. 



Muscle hnpressions and Pallial Line. — -Anterior muscle impres- 

 sion rather small, cuneate, rounded ventrally. Posterior muscle 

 impression rotund. Pallial line and sinus often obscure, the sinus 

 very broad and deep, partially confluent ventrally with the pallial 

 line. 



Dimensions. — Altitude, 6.4 mm. Latitude, 10.0 mm. 



Type Locality — Neill's Eddy Landing, Columbus County, North 

 Carolina. Waccamaw Formation. 



Observations — The most closely allied species is Donax emmonsi 

 Dall. From this form, Donax cuneola is separated by the higher, 

 more tumid umbones, the more oblique anterior, the more rounded 

 posterior and the straighter ventral margin, the faintlj^ indicated 

 anterior angulation, the more strongly differentiated posterior 

 area, and the heavier, more compact hinge teeth From Donax 

 fossor Say, it is distinguished by the relatively greater altitude, 

 the more nearly central umbones, and the less produced anterior 

 margin. 



Distribution.— Y or Jdown Formation. Yorktown, York County; 

 1| miles northeast of Suffolk, Nansemond County, Virginia. Dup- 

 lin Formation. 4 miles northeast of Fairmont, Robeson County, 

 North Carolina. Muldrow's Place, 5 miles southeast of Mayes- 

 ville, Sumter County, South Carolina. Waccamaw Formation. 

 Walker's Bluff, Cape Fear River, Bladen County; Neill's Eddy 

 Landing, 3 miles north of Cronley, Cape Fear River, Columbus 

 County, North Carolina. 



Collections. — U. S. National Museum. Johns Hopkins Uni- 

 versity. The Academy of Natural Sciences of Philadelphia. 



Macoma carolinensis new species.. Plate III, flgs. 5, 6, 7. 



General Characters. — Shell thin. Liflated. Irregularly ovate, 

 with a very feeble posterior flexure. Slightly inequivalve, the 

 right valve a little higher than the left. Inequilateral. Anterior 

 dorsal slope gentle, merging gradually into the broadly rounded 

 anterior end. Posterior end blunt. Anterior dorsal and ventral 

 margins usually converging at a very low angle in the right valve, 

 parallel in the left. Posterior dorsal margin declining much more 



