MARYLAND GEOLOGICAL SURVEY 193 



land, South Carolina, and Florida and in the Eecent it ranges from 

 Massachusetts south to- Mexico and Brazil. 



Width, 122 mm. ; height, 48 mm. 



Occurrence. — Talbot Formation. Wailes Bluff near Cornfield Har- 

 bor, and Bay Shore south of Cedar Point, St. Mary's County. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 and IT. S. National Museum. 



Superfamily MYACEA. 

 Family CORBULIDAE. 



Genus CORBULA (Brugniere) Lamarck. 



Section CUNEOCORBULA Cossmann. 



CORBULA CONTRACTA Say. 



Plate LIU, Figs. 1-4. 

 Corbula contracta Say, 1822, Jour. Acad. Nat. Sci. Phila., vol. ii, 1st ser., 



p. 312. 

 Corbula contracta Holmes, 1858, Post-Pi. Fos. S. C, p. 56, pi. viii, fig. 17. 

 Corbula (Cuneocorbula) contracta Dall, 1898, Trans. Wagner Free Inst. 



Sci., vol. iii, pt. iv, p. 855. 



Description. — " Shell transversely subovate ; valves subequal, regularly 

 and profoundly striated transversely; beaks not prominent, nearly cen- 

 tral, one side rounded and the other subacute; basal margin contracted 

 near the middle, and one-half of the length of the edge of one valve con- 

 cealing one-half of the edge of the opposite valve." Say, 1822. 



This species is rare in the Maryland Pleistocene. It is a small form 

 and is not easily detected except after the materials collected have been 

 carefully washed. 



The earliest appearance of the species is in the Pliocene of North Caro- 

 lina and Florida. It has been found in the Pleistocene of Massachusetts, 

 New Jersey, Maryland, and South Carolina and in the Eecent ranges 

 from Cape Cod to Jamaica. 



Width, 7.25 mm.; height, 4.25 mm. 



Occurrence. — Talbot Formation. Wailes Bluff near Cornfield M ar- 

 bor, St. Mary's County. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 and II. S. National Museum. 

 14 



