ORTMANN: monograph of the naiades of PENNSYLVANIA. 73 



Other localities represented in the Carnegie Museum: 



Ohio-drainage: 

 Ohio River, Beech Bottom, Brooke Co., West Virginia (W. F. Graham); Toronto, Jefferson Co., Ohio; 



Clarington, Monroe Co., Ohio; St. Marys, Pleasants Co., West Virginia; Portland, Meigs Co., 



Ohio; Portsmouth, Scioto Co., Ohio. 

 Tuscarawas River, Ohio (Holland collection). 



Cumberland- Tennessee-drainage : 

 Cumberland River, Clarksville, Montgomery Co., Tennessee (R. E. Coker donor). 

 Tennessee River, Tuscumbia, Colbert Co., and Florence, Lauderdale Co., Alabama (H. H. Smith). 

 Paint Rock River, Paint Rock, Jackson Co., Alabama (H. II. Smith). 

 Tennessee River, Knoxville and Brabsons Ferry, Knox Co., Tennessee. 

 French Broad River, Boyd Creek, Sevier Co., Tennessee. 

 Holston River, Mascot, Knox Co.; Hodges, Jefferson Co.; Noeton and Holston Station, Grainger Co., 



Tennessee. 

 Clinch River, Solway, Knox Co.; Edgemoor, Clinton, and Offutt, Anderson Co., Tennessee; Needham 



Ford, Union Co., Tennessee (B. Walker donor). 



Distribution and Ecology in Pennsylvania (See fig. 8) : The typical form of 

 P. obliquum is restricted in Pennsylvania to the three large rivers, the Ohio, Alle- 

 gheny, and Monongahela. In the Allegheny it is found as high up as Armstrong 

 Co., but is not very abundant there. In the Monongahela, judging from the large 

 number of specimens collected by G. A. Ehrmann, it must have been at one time 

 abundant in the vicinity of Charleroi, but we do not know how far it ascended the 

 river. In the Ohio below Pittsburgh it is a common shell. Farther down, it is 

 extremely abundant, and is the prevailing species, at lea'st locally. It is the shell, 

 which largely contributes in forming the shell-banks, in rather deep, steadily flowing 

 water, and, next to the "mucket" {Actinonaias ligamentina) , it is the sheU most 

 highly valued by the clam-diggers. In Pennsylvania, it is present also in riffles, 

 and immediately above them, in strong current, and among coarse gravel. 



General distribution: Type locality, Ohio River (Lamarck). 



On account of the great confusion prevailing with regard to this species, it is 

 hard to make out the limits of its distribution, but it is certain that it chiefly 

 inhabits the systems of the Ohio, Cumberland, and Tennessee Rivers. In the 

 Ohio-drainage it docs not go much into the tributaries, but is known from the 

 Muskingum-Tuscarawas River in Ohio (Sterki, 1907a), and from the Wabash in 

 Indiana (CaU, 1896a and 1900). It occurs also in the Mississippi in Illinois (Baker, 

 1906), and goes northward into Wisconsin and Minnesota. It also has been 

 reported from the Alabama River (Lewis, 1877, and Simpson, 1900), but this is 

 doubtful. I have not seen any specimens of it in the collections made there by 

 H. H. Smith. 



