ORTMANN: monograph of the naiades of PENNSYLVANIA. 329 



Big Beaver Creek, Mercer Co., Ohio (C. Goodrich) (Wabash-drainage). 



West Fork River, Lynch Mines, Harrison Co.; West Milford, Harrison Co. (W. F. Graham); Lightburn, 



Lewis Co., West Virginia. 

 Little Kanawha River, Grantsville, Calhoun Co. ( W. F. Graham) ; Burnsville, Braxton Co., West Virginia. 

 North Fork Hughes River, Cornwallis, Ritchie Co., West Virginia. 



Tennessee-drainage : 



Duck River, Columbia, Maury Co., Tennessee (G. H. Clapp, donor). 



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



Bear Creek, Burleson, Franklin Co., Alabama (H. H. Smith). 



Flint River, Maysville, Madison Co., Alabama (H. H. Smith). 



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



Nolichucky River, Chunns Shoals, Hamblen Co., Tennessee. 



Holston River, McMillan and RLiscot, Knox Co.; Turley Mill and Holston Station, Grainger Co.; 

 Austin Mill, Hawldns Co., Tennessee. 



South Fork Holston River, Pactolus, Sullivan Co., Tennessee. 



North Fork Holston River, Rotherwood, Hawkins Co., Tennessee; Hilton, Scott Co., Virginia; Mendota, 

 Washington Co., Virginia. 



Clinch River, Sol way, Knox Co.; Edgemoor and Clinton, Anderson Co.; Black Fox Ford, Union Co.; 

 Clinch River Station, Claiborne Co.; Oakman, Grainger Co., Tennessee; Speers Ferry and Clinch- 

 port, Scott Co., Virginia.- 



Powell River, Combs, Claiborne Co., Tennessee. 



Distribution and Ecology in Pennsylvania (See fig. 34) : This is a widely dis- 

 tributed species in the Ohio-drainage in western Pennsylvania, but is not found 

 anywhere in great numbers. In the Ohio proper below Pittsburgh I found only a 

 few dead shells. It is present in the Beaver-drainage, but is not very abundant. 

 In the Allegheny in Armstrong Co. it is not rare, and in this region enters some 

 of the tributaries, as Crooked Creek, and farther up, French Creek, penetrating 

 weU into the headwaters. It has not been found in the Allegheny above Oil City. 



In the jMonongahela-drainage, this species is extremely rare, and I found it 

 only in Dunkard Creek. However, farther up in the headwaters in West Virginia 

 it is rather abundant, as in West Fork River, where at Lynch Mines I secured the 

 largest nimiber of specimens in all my collecting. 



In addition this species is present in Lake Erie, but here it is extremely rare. 

 I found only a single dead shell in Presque Isle Bay. 



Truncilla triquetra distinctly belongs to those species, which inhabit riffles. 

 Wherever I found it, it was on riffles, and (at low stage) in quite shallow water, 

 in strong currents. Here it is deeply buried, and only the trimcated posterior 

 slope is exposed, so that in the natural position the shell offers a verj- peculiar 

 aspect; only the flat, broadly lanceolate posterior slope is exposed to view, differ- 

 ing entirely from the dark slit generally seen in other Naiades (formed by the 



