256 MEMOIRS OF THE CARNEGIE MUSEUM. 



Clinch River, Solway, Knox Co.; Edgemoor and Offutt, Anderson Co.; Clinch River Station, Claiborne 



Co.; Oakman, Grainger Co., Tennessee; Clinchport, Scott Co., Virginia. 

 Powell River, Combs, Claiborne Co., Tennessee. 



Mississippi and westward: 

 Mississippi River, Muscatine, Muscatine Co., Iowa (Hartman collection); Moline, Rock Island Co., 



Illinois (P. E. Nordgren). 

 Osage River, Warsaw, Benton Co., Missouri (W. I. Utterback). 

 Bull Creek, Miami Co., Kansas (C. Goodrich, donor) (Osage-drainage). 

 Kansas and Wakarusa Rivers, Lawrence, Douglas Co., Kansas (R. L. Moodie). 



Distribution and Ecology in Pennsylvania (See fig. 26): This species has two 

 ranges in Pennsylvania: one in the Ohio system; the other in Lake Erie. In the 

 latter it is found in Presque Isle Bay, but is comparatively rare. 



In the Ohio system, it belongs to the three large rivers, the Ohio, Allegheny 

 and Monongahela, and ascends the Allegheny to Armstrong Co., but is rare there: 

 Marshall's record from Warren County should be disregarded. In the Monon- 

 gahela, it is known from the neighborhood of Charleroi, but must once have gone 

 farther up, to near the West Virginia state-line, for it is found (although very 

 rarely) in the lower part of Dunkard Creek in Greene Co. There is only one 

 other instance known where it enters a small tributary, this is Little Beaver Creek 

 in Beaver County, and there also it is very rare. None of the other tributaries of 

 the Ohio system contains this species, which is most remarkable especially in the 

 case of the Beaver River, where this species has never been found. 



In the Ohio below Pittsburgh P. alata is common, sometimes even very abun- 

 dant, and here it is found in riffles, in fine and often rather coarse gi'avel. It is a 

 rather active species, crawling around a good deal. It is also found on the shell- 

 banks at Industry and Shippingjjort, associated with the other bank-forming 

 species, in gravel and strong, steady currents. 



In Lake Erie (Presque Isle Bay), it is found in the characteristic sand of the 

 north shore of the bay, in from two to three feet of water, and seems to prefer the 

 open shores (not covered and fringed by rushes). 



General distribution: Type locality, Lake Erie (Say). 



The centre of distribution is in the northern section of the interior basin, in 

 the Mississippi and Ohio Rivers, and their tributaries. In the Ohio its upper 

 boixndarj^ has been located in western Pennsylvania. Like Paraptera fragilis, 

 it passes northward into the northern drainage systems of the Red River of the 

 North, of Hudson Bay and of the St. Lawrence. In the latter it is found prin- 

 cipally in the lower lakes and their tributaries, as far as Ottawa (Bell, 1859; Whit- 

 eaves, 1863) and it also goes into Lake Champlain, Lake George, and the Hudosn- 



