290 ORTMANN— THE ALLEGHENIAN DIVIDE. [April 1 8, 



far as to ascertain the great contrast which exists between it and 

 the river systems to the north of it. Thus my investigations cover, 

 on the western side of the Alleghenies, the drainages of the Allegheny 

 and Monongahela rivers (upper Ohio), of the Kanawha River, and 

 , in part only of the Big Sandy, Licking and Tennessee rivers (Clinch 

 and Holston). On the eastern side, the systems of the Delaware, 

 Susquehanna, Potomac, and of the upper James and Roanoke are 

 included. 



It is believed that the faunistic facts with regard to these rivers 

 are reasonably complete and that my collections in them have fur- 

 nished the knowledge, not only of what is present in them, but also 

 of what is absent; under circumstances, this latter fact may even 

 be more valuable than positive records. 



Chapter i. 



Statement of Distributional Facts in Najades. 



The nomenclature of the Najades is that introduced by myself 

 in some recent publications (chiefly Ortmann, 1912a, pp. 222 fL). 

 The lists give the number of distinguishable forms, no matter 

 whether they are species or varieties. Unless otherwise stated, all 

 information is founded upon the writer's personal experience, and 

 the specimens from the various localities are preserved in the col- 

 lections of the Carnegie Museum in Pittsburgh. The great mass of 

 new distributional facts secured by the writer makes it imperative to 

 give them in full. For this reason, the present chapter is somewhat 

 lengthy and contains much that is uninteresting reading for those 

 which are not specialists. But this is unavoidable. 



A. WESTERN SIDE OF ALLEGHENIES. 

 I. The Upper Ohio Fauna in General. 



First I give a complete list of species (or forms) found in the 

 upper Ohio drainage, above Smith Ferry, Beaver Co., Pa., in the 



Unionidse of the Alabama River system have been derived from the Tennes- 

 see," and White (1904, p. 38) directly says that the upper course of the orig- 

 inal Waiden Gorge River (tributary to Tennessee) has been captured by Con- 

 asauga River (tributary to Oostanaula and Coosa Rivers). 



