Ixxiv FISHES OF ILLINOIS 



THE GENERAL DISTRIBUTION 



Most of the 150 species of the native fishes of IlUnois range 

 far and wide in all directions beyond its narrow boundaries, 

 thus illustrating the breadth and the simplicity of our geo- 

 graphical affiliations with the surrounding territory; but a con- 

 siderable number, on the other hand, coming into Illinois from 

 one direction, do not pass beyond it in another, some part of 

 the boundary of the general area of their distribution passing 

 through our state. Several southern fishes go no farther north 

 than Illinois; some northern fishes go no farther south; some 

 eastern species find here their western limit; and a few western 

 species range no farther east. The comparison of these geo- 

 graphical groups whose areas overlap by their borders here in 

 Illinois is a matter of special interest to the student of distribu- 

 tion, because it is in them that we find indicated the more 

 remote affinities of our fish fauna, and from them, if anywhere, 

 we may glean suggestions of its various origins. 



It will be convenient for a discussion of this subject to 

 divide the general expanse over which Illinois fishes are dis- 

 tributed, into the following twelve districts: 1, the upper Mis- 

 sissippi Valley, including the Missouri and its tributaries; 2, the 

 lower Mississippi Valley, including the Ohio and its tributaries; 

 3, the far North, extending northward from the headwaters of 

 the Mississippi, east to the Lake Superior drainage, and west 

 to the Rocky Mountains; 4, the far Northwest, separated from 

 the preceding by the Rocky Mountains range; 5, the Great 

 Lake region; 6, the district of Quebec and New England; 7, the 

 Hudson River district; 8, the north Atlantic drainage, from New 

 England to the Chesapeake Bay; 9, the south Atlantic, from 

 the Chesapeake Bay to Florida; 10, the peninsula of Florida; 11, 

 the east Gulf district, bounded by the Mississippi drainage on 

 the west; and 12, the west Gulf district, bounded by the Missis- 

 sippi drainage on the east, and extending west and south to 

 include the Rio Grande and its tributaries. The following 

 table shows the recorded distribution of our species over the 

 territory so divided. 



