ORTMANN: monograph of the naiades of PENNSYLVANIA. 



169 



Meadville), while it is rather frequent in Conneaut Outlet and in the lake itself. 

 This pecuhar feature will be discussed elsewhere. It suffices to mention here that 



Fig. 16. 

 • Anodontoides ferrussacianus. 

 + Do. feruss. buchanensis. 



all these systems (Beaver, Conneaut, French Creek) have been either naturally or 

 artificially closely connected in the past. 



Wherever I found this species in abundance it preferred comparatively quiet 

 parts of the creeks, with little or no current, and with sandy-gravelly bottoms, 

 with some admixture of mud. It also occurs in lakes, as for instance Conneaut 

 Lake, and exhibits here the tendency to become more inflated, approaching thus 

 the var. buchanensis. In Conneaut Lake it is found chiefly on sandy bottom at 

 the south end of the lake, but also elsewhere in gravel. It seems to be averse to 

 larger streams with strong currents and rough bottoms. 



Baker (1898a) says that it is a species frequenting muddy bottoms. 



General distribution: Type locality, Ohio River, Cincinnati, Ohio (Lea). 



According to Simpson this species is found generally in the Mississippi-drainage 

 area; in the St. Lawrence system; the Red River of the North; the Saskatchewan 

 River; and doubtfully in Connecticut (according to Linsley, 1845, at Whitney- 

 ville, New Haven Co.). 



In the east its range certainly extends into New York state, as far as the 

 Hudson River and the headwaters of the Susquehanna and Delaware systems 

 (Marshall, 1895),^-^ and it is frequent in the St. Lawrence-drainage in a form 

 which is typical (see our specimens from the Genesee River). I have it also in 

 rather typical development from a tributary on the Canadian side of Lake Ontario, 

 and it has been reported from Montreal and Ottawa. Farther. west, its northern 

 boundary is uncertain, but it surely advances rather far northward, as is shown 

 by the localities given by Walker (1898) for Michigan (Charlevoix, upper Penin- 



"" But it is not found in Pennsylvania in these rivers. 



