320 MEMOIRS OF THE CARNEGIE MUSEUM. 



the same range, as that given by him for L. cariosa. But, as we have seen, in 

 the south L. cariosa is doubtful. 



The species has been reported from Maine (Marshall, 1895; Lermond, 1909), 

 from Massachusetts (Earle, 1835; Gould-Binney, 1870; Marshall, 1895), from 

 Connecticut (Linsley, 1845) (See also New England localities given by Johnson, 

 1915). It is known from the Hudson in New York, and is said to go up here to 

 Albany and the Mohawk River, Herkimer Co. (Marshall). In Pennsylvania, it 

 is restricted to the lower Delaware, and the lowlands near to it. It has been foimd 

 in the lower Schuylkill and also Wissahickon Creek. According to specimens I 

 have seen in the Philadelphia Academy, it is abundant in the ditches of the meadows 

 near League Island. It is miknown from the Susquehanna and Potomac drainages 

 in Pennsylvania, although known from the lower Potomac in the District of Colum- 

 bia (Marshall), Prince George Co., Maryland (Lea, Obs. X, 1863, p. 456), and 

 Fairfax Co., Virginia (Marshall). Rhoads (1904) reports it from Seaford, Sussex 

 Co., Delaware, and farther south it is abundant in the lower James River, Virginia 

 (Conrad, 1836) and according to the same author in "most tide-waters north of 

 the Savannah River." The most southern record is that of Simpson from the 

 Ogeechee River in Georgia. 



In Pennsylvania, L. ochracea is decidedly rare, and restricted to the tide- 

 waters of the Delaware. It is not at all coextensive with L. cariosa, since the 

 latter ascends the rivers for a considerable distance. The same seems to be true 

 in other parts. Most of the exact localities known are in the tidewater-regions 

 of the Atlantic streams, and Conrad calls especial attention to this. Thus the 

 ecological preferences of this species seem to be for the estuaries of our large rivers. 

 In the Hudson it goes up quite far, but in the vicinity of Albany it has been reported 

 chiefly from canals, and it seems that it also frequently inhabits canals and ponds. 

 I found it myself in the Delaware-Raritan Canal in New Jersey. Thus the species 

 differs ecologically from L. cariosa. It is a form of estuaries, ponds, canals, and 

 ditches, probably with more or less muddy bottoms, while L. cariosa favors large 

 rivers, with sandy and gravelly bottoms and strong currents. A closer study of 

 these conditions is very desirable (See Ortmann, 1913a, pp. 325, 368). 



Lampsilis orbiculata (Hildreth) (1828). 

 Lampsilis orbiculata (Hildreth) Simpson, 1914, p. 76. 



Plate XX, fig. 8; Plate XXI, figs. 1, 2. 

 Records from Pennsylvania: 



Clapp, 1895 (Allegheny Co.) 

 Ortmann, 1909&, p. 190. 



