On the General and Interior Distribution of Illinois Fishes

Abstract

The geography of Illinois is, in its most obvious features, so simple and so monotonous that one naturally expects a similar simplicity and monotony in the geographic distribution of its plants and animals. The plan of its hydrography is as little complicated as the geography of its land areas. Surrounded on more than two thirds of its circumference by three large rivers, the Mississippi, the Ohio, and the Wabash, with Lake Michigan covering a narrow strip at its northeast corner and draining a bordering region of scarcely greater area, its other waters flow southwestward into the Mississippi and southward into the Wabash and the Ohio, all mingling finally opposite its southernmost extremity for their journey to the Gulf. Its principal watersheds are inconspicuous ridges or slightly elevated plains, most of them originally more or less marshy, and the headwaters and tributaries of its various stream systems so approach and intermingle that in times of flood they formed an interlacing network, through which it would seem that a wandering fish might have found its way in almost any direction and to almost any place.