246 MEMOIRS OF THE CARNEGIE MUSEUM. 



A labama-drainage : 

 Coosa River, Wetumpka, Elmore Co.; Weduska Shoals and Wilsonville, Shelby Co.; Riverside and 

 Lock 4, St. Clair Co.; Minnesota Bend, Cherokee Co., Alabama (H. H. Smith). 



Distribution and Ecology in Pennsylvania (See fig. 25) : In Pennsylvania this 

 species is found only in the Ohio, Allegheny, and Monongahela. In the Alle- 

 gheny it goes to southern Armstrong County, where it is quite rare. In the Monon- 

 gahela it is known only from Charleroi in Washington County, and on the opposite 

 side in Westmoreland Count}'. Below Pittsburgh it is not a rare shell, and has 

 been found in considerable numbers in the riffles and the shell-banks in coarser pr 

 finer gi'avel and in strong currents. 



Farther down the Ohio this is a common shell in the shell-banks, and is regu- 

 larly taken by the clam-diggers. 



General distribution: Type locality, FaUs of the Ohio, at LouisviUe, Kentucky 

 (Rafinesque). 



This species primarily belongs to the large rivers of the interior basin. In 

 the Ohio its extreme upstream range reaches Pennsylvania. Farther down it is 

 mainly restricted to this river (Sterki, 1907a). In Indiana it also occurs in the 

 larger tributaries, the Wabash and West White Rivers (Call, 1896a, 1900) and has 

 crossed over, probably very recently, into the Maumee at Fort Wayne, Indiana 

 (Goodrich, 1914). This is the only known record from the lake-drainage. In 

 Illinois it is also found. in the Wabash, Kaskaskia, and Illinois Rivers, in the latter 

 as high up as Peoria County (Forbes & Richardson, 1913), and to the Kankakee 

 (Baker, 1906). It ascends the Mississippi as far as Minnesota (Grant, 1886; 

 Holzinger, 1888). It is also found in the Cumberland River (Wilson & Clark, 

 19126 and 1914) and in the Tennessee it goes up accordmg to Lewis (1871) to the 

 "Holston" near Knoxville, but it must be born in mind that the "Holston" of 

 Lewis is the Tennessee. I found it there myself and also in the lower Clinch in 

 Anderson County, but not in the Holston proper. 



West of the Mississippi this species is found in Missouri (Utterback, 1916) 

 in southeastern Kansas (Scammon, 1906), Arkansas and Oklahoma (See Call, 1895; 

 Wheeler, 1918; and the material in the Carnegie Museum) but its exact south- 

 western boundary has not been determined. 



In addition it is present in the Alabama and Tombigbee drainages in Alabama 

 (Lewis, 1877; Call, 1885; Simpson, 1900; and material in Carnegie Museum) 

 and has reached Georgia in the Etowah River (CaU, 1885). 



Everywhere it seems to favor the "mussel-beds" in the larger rivers. Scam- 

 mon (1906) reports it from rocky riffles in Kansas, but says that it occurs in a 



