ORTMANN: monograph of the naiades of PENNSYLVANIA. 51 



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



Virginia. 

 Coal River and Little Coal River, Boone Co., West Virginia (Hartman collection)." 



Tennessee-drainage : 

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

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

 Holston River, Mascot, Knox Co., Tennessee. 



Mississippi-drainage and westward: 

 Peoria Lake, Illinois River, Illinois (Hartman collection). 

 Mississippi River, Muscatine, Muscatine Co., Iowa (Hartman collection). 

 INIeraniGC River, Meramec Highlands, St. Louis Co., Missouri (N. M. Grier). 

 Black Rock River and Spring River, Black Rock, LawTence Co., Arkansas (H. E. Wheeler). 

 Spring River, Williford, Sharp Co., Arkansas (H. E. Wheeler)." 

 White River, Cotter, Baxter Co., Arkansas (A. A. Hinklej')- 

 Ouachita River, Arkadelphia, Clark Co., Arkansas (H. E. Wheeler). 

 Neosho River, Miami, Ottawa Co., Oklahoma (F. B. Isely). 



A labama-drainage : 

 Sipsey River, Texas, Marion Co., Alabama (H. H. Smith). 

 Coosa River, Wilsonvillc, Shelby Co., and Riverside, St. Clair Co., Alabama (H. H. Smith). 



Distribution and Ecology in Pennsylvania (See fig. 6): In Pennsylvania this 

 species is restricted to the three large rivers, the Ohio, Allegheny, and jNIonongahela. 

 In the Allegheny it goes up a little beyond the middle of Armstrong County. From 

 the ]\Ionongahela it is known only from one locality, but it must have at one time 

 ascended into West Virginia, for it occurs in the West Fork River. 



Wherever found it is not rare, but it is most abundant in the Ohio below 

 Pittsburgh. Here it favors the same places as most other species: coarse gravel 

 in swiftly running water, and it helps to compose the shell-banks, where such are 

 present (at Shippingport and Industry). This agrees with Scammon (1906, p. 

 350), who says that gravel-bars are its favorite habitat. In the Ohio below Wheel- 

 ing it is frequently taken by the clam-diggers out of deep water in strong and 

 steady currents. 



General distribution: Type locality, Kentucky River (Rafinesque). 



The general distribution, as given by Simpson (1900) is: " ^Mississippi-drainage 

 area, except its southern portion, extending to the Tennessee and Arkansas River." 

 This is quite correct, and it is to be particularly noted, that toward the east and 

 north, this species does not cross over into any other drainage-system. As we 

 have seen, in western Pennsylvania it does not advance far up into small streams, 



" See above p. 49. Specimens from West Fork, Little Kanawha, and Coal Rivers all (together 

 six) represent the form irardi. 



*" This specimen is a good representative of the var. ivardi. 



