316 ORTMANN— THE ALLEGHENIAN DIVIDE. [April 18, 



local, and Eurynia nasuta has been reported farther south on the 

 Coastal Plain (as far as North Carolina by Simpson; from James 

 River by Conrad, '36 ; from the lower Potomac by Dewey, '56 ; and 

 Marshall, '95). But these localities should be confirmed, since this 

 species has been frequently confounded with Elliptio productus and 

 fisherianus. According to Rhoads ('04), it is also in Sussex and 

 Kent Cos., in Delaware. 



The Susquehanna drainage extends not only into the Allegheny 

 Valley and into the mountains, but clear through the mountains, and 

 encroaches upon the Allegheny plateau. All of the species men- 

 tioned above go up into this region, but two of them have only a 

 limited distribution, and seem to be restricted to the larger rivers. 

 These are Lampsilis radiata and L. cariosa. Both of them go in the 

 North Branch to the New York state line. In the Juniata is only 

 L. cariosa (up to Huntingdon, Huntingdon Co.), and in the West 

 Branch both go up at least to Williamsport, Lycoming Co. In the 

 real headwaters there are only seven species, and they are not always 

 associated at a particular locality (generally there are only from 

 three to six together). 



One locality is of special interest : this is Cush Cushion Creek, 

 in Greene Twp., Indiana Co. This is the most western point to 

 which the Susquehanna fauna advances, and the following species 

 are here : 



1. Elliptio complanatus (Dillw.) 



2. Symphynota tappaniana (Lea) 



3. Alasmidonta varicosa (Lam.) 



4. Strophitus edentulus (Say) 



Not very far from here, in Chest Creek, Patton, Cambria Co., 

 I found : 



1. Elliptio complanatus (Dillw.) 



2. Symphynota tappaniana (Lea) 



3. Alasmidonta undulata (Say) 



4. Strophitus edentulus (Say) 



Also Anodonta Cataracta Say has been found in this region, in 

 Beaver Dam Creek, Flinton, Cambria Co. Thus there would be six 



