I9I3.1 ORTMANN— THE AT.LEGHENIAN DIVIDE. 305 



In the lower Tygart, tlie fauna has been destroyed by polhition. 

 The upper part, above Elkins, contains only two species : 



Synipliynofa costata (Raf.) 

 Stro/^hifiis cdcninlns (Say) 



The upper part of the r>uckhannon drainage has one species : 



Strophifiis cdciitulns (Say) 



I found this not in the river itself, which is dammed and has 

 slack water, but in a small tributary, French Creek, at Hampton, 

 Upshur Co, W. Va. 



Thus, in these mountain streams tributary to the upper Monon- 

 gahela, we meet with conditions entirely different from those in the 

 upper Allegheny and its tributaries : the rich Ohio fauna, only 

 slightly depauperated, goes up to a certain point, up to the lower end 

 of a canyon, which represents an extremely rough part of these 

 rivers. This is best observed in the case of the Cheat (list no. ii), 

 while in the others pollution has destroyed the original conditions. 

 But we may easily imagine what these were when we look at the 

 fauna of the plateau stream. West Fork River (see list lo). At 

 the lower end of the canyon the fauna suddenly stops, and above the 

 canyon, in the high valleys, where the rivers are more quiet, very 

 few species, one or two, are found, if such are present at all. It 

 should be noted that one species, Strophitus edentiilus, is found in 

 all three rivers, which have shells, but that Syniphynota costata is 

 only in the Tygart. 



Thus the canyon apparently forms here a natural barrier. 



V. Fauna of the Kanawha River. 



Farther to the south we have the Kanawha drainage in West 

 Virginia. The fauna of the Kanawha itself is unknown, for this 

 river is much polluted, and has been transformed into a series of 

 pools by dams, conditions unfavorable for Najad-life. 



However, there are two tributaries in the plateau-region, which 

 contain shells. The first is Elk River. Here I collected repeatedly 

 and was able to secure the following species. Those marked * are 

 from the uppermost station, at Sutton, Braxton Co., W. Va. 



