10 



MEMOIRS OF THE CARNEGIE MUSEUM. 



Distribution and Ecology in Pennsylvania (See fig. 2) : This species belongs in 

 Pennsylvania to the larger rivers, the Ohio, Allegheny, and Monongahela, to the 

 Beaver as far as the lower Mahoning, and to the lower Cheat. It has never been 

 found in any other tributary of the upper Ohio system. It prefers heavy shingle 

 and gravel, in a strong current, and is especially adapted to this habitat by its 



Fig. 2. 



■ Fusconaia subrotimda. 



• Fusconaia suhrotunda kirtlandiana. 



subglobular shape and heavy shell. In the Allegheny it occurs as high up as 

 Kelly in Armstrong County; above this point, the river is largely polluted, so 

 that the upper limit of its former distribution cannot be now ascertained, but it is 

 positively missing in the upper Allegheny above Oil City, and is not represented 

 by its variety kirtlandiana, while the latter takes its place in French Creek. In 

 the upper parts of the Beaver-drainage it is also gradually replaced by kirtlandiana. 

 Particulars about its range in the Monongahela are wanting, but it possiblj^ reached 

 a little beyond the West Virginia line. It is found in the lower Cheat, and has 

 also been found in the Indian Garbage heap at Point Marion, opposite the mouth 

 of the Cheat (See Ortmann, 1909c). 



General Distribution: 



Type locality; Ohio (Lea). 



This species is positively known only from the Ohio-drainage, ranging from 

 Pennsylvania westward to Illinois, and is generally restricted to the Ohio River 



Tennessee region this species is represented by a dwarfed race, commonly called U. pihiris Lea. Also 

 in Elk River, West Virginia, I have discovered a dwarfed race, which I have called var. leucogonn (Ort- 

 mann, 1913b, p. 89), but I doubt now the propriety of distinguishing this by a name. 



