Article X. — Studies on the Biology of the Upper Illinois River. 

 By Stephen A. Forbes and R. E. Richardson. 



The Illinois River is peculiarly characteristic of the State of Illi- 

 nois, and, next to the prairies, was its leading natural feature. The 

 level richness of the central plateau of the state is reflected in the 

 turbid waters and the broad sluggish current of the stream; and 

 its wide bottom-lands, originally covered with huge trees, completely 

 flooded when the river is highest, and holding many marshes and 

 shallow lakes at its lowest stages, are a relic of the time, not so very 

 far remote, when the limpid waters of the Great Lakes rolled down 

 its valley in a mighty flood on their course to the southern gulf. It 

 was not an accident that this river was the first great artery of 

 transportation into and through the state, or that the first colonial 

 settlement and the first fortified post in Illinois were established on 

 its banks. After the railroads had deprived it of its commerce it 

 was discredited and neglected for many years, and the second city 

 in the country and the second city of the state have long used it as 

 a mere convenience for the discharge of their organic wastes. 



These are temporary conditions, however, and the time seems 

 now at hand when the people of Illinois will learn to appreciate and 

 develop this great gift of nature in the various directions in which 

 it may be made to serve their interests and their pleasures. Its fre- 

 quently beautiful and occasionally picturesque scenery is attracting 



ERRATA 



Page 4Q7, line 9 from bottom, for ncglible read negligible, and in footnote, 

 for Austalt read Austalt. 



Page 498, line 4 from bottom, for Lockport read ChiUicothe. 



Page 500, line 13 from bottom, after up insert in. 



Page 501, line 2 from bottom, for dissolving read dissolved. 



Page 504, line 23, for gryina read gyrina. 



Page 506, line 11, for vernata read ternata. 



Page 507, line 3 from bottom, for Mazon read wagon. 



Page 513, line 19, for Nepa read Zaitha. 



Page 525, line 22, and page 536, lines 21 and 24, for Ekmann read Ekman. 



Page 532, line i, for Ancyclus read Ancylus. 



Page 551, line 7, for 00 read 512. 



Plate LXXXV, for 7 read yc. 



