ORTMANN: monograph of the naiades of PENNSYLVANIA. 81 



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

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

 Licking River, Farmer, Rowan Co., Kentucky. 



Tennessee-drainage: 

 Holston River, Hodges, Jefferson Co.; Noeton, Grainger Co., Tennessee. 

 Clinch River, Solway, Knox ('o., Tennessee. 



West of Mississippi: 

 James River, Galena, Stone Co., Missouri (A. A. Hinkley). 

 White River, Garfield, Benton Co., Arkansas (R. L. Moodie). 



Distribiitio7i and Ecology in Pennsylvania (See fig. 8): In Pennsylvania, this 

 form is widely distributed. It is especially abundant in the Beaver-drainage, 

 and also in that of the upper Allegheny, going up far into the headwaters, reaching 

 into Beaver and French Creek, Crawford and Erie Cos., and in the uppermost Alle- 

 gheny, McKean Co. In the Monongahela-drainage, it is rare, at least in Penn- 

 sylvania, and found only in Dunkard Creek, but formerly it surely existed else- 

 where in smaller creeks, which are now polluted. It becomes more abundant 

 again in the headwaters of the Monongahela in West Virginia. 



It is distinctly a form of the smaller creeks, and locally quite plentiful in them. 

 It prefers sand and fine gravel, in or below riffles, where the current is rather 

 lively, and generally it is deeply buried. It avoids coarse gravel, but may be found 

 now and then in rough places. 



As has been stated, farther down in the larger rivers, it passes into P. obliqtium 

 catillus, and with the change of the shape of the shell, there is also a change in its 

 ecological preferences, or perhaps it might be true to say that the latter very likely 

 is the cause of the former change. We have here a good example of the correlation 

 of habitat and shape. P. obliquum coccineum is distinctly an ecological race of 

 P. obliquum (and its variety catillus) characteristic of the fine gravel and sand 

 of the smaller streams. In the Ohio below Pittsburgh coccineum is practically 

 absent, only a single individual having been found. 



Its presence in Conneaut Creek, a tributary of Lake Erie, should be noted. 

 It appears that this form is not derived from the form found in Lake Erie {pau- 

 perculum), but is identical with the form present in the upper Beaver and French 

 Creek-drainages. A crossing over the divide is in this case suggested, and it should 

 not be forgotten, that the old Beaver Canal (now obliterated) once connected 

 these systems. 



General distribution: Type locality, Mahoning River, near Pittsburgh (Conrad) 

 (See above, p. 78, footnote 53). 



Simpson (1900) gives for this form: "entire upper Mississippi-drainage," 



