MISSISSIPPI 



RIVER 

 DRAINAGE 



LOWER 

 UlSStSSIPPi 



Fig, 2. — Drainage systems and some of the principal streams 

 of Illinois. The heavy curved lines indicate drainage systems of 

 three categories, based on size: (I) the Great Lakes and the 

 Mississippi River; (2) the Wabash, the Ohio, and the Mississippi 

 (Upper, Middle, and Lower); and (3) other rivers named. The 

 short, heavy line to the right of each of the designations Upper 

 Mississippi, Middle Mississippi, and Lower Mississippi shows the 

 downriver limit of one of the three sections of the river as under- 

 stood in this paper. 



througliDut its range, and a species listed as sporadic may 

 be locally abundant. 



Distribution is usually expressed in terms of sections 

 of the state, such as northern half, southern fourth, and 

 extreme northeastern part ( Fig. 1 ) . In some instances, 

 distribution is stated in terms of specific drainage systems 

 or waters, such as Kankakee drainage system, upper Wabash 

 drainage system. Lake Michigan, and middle and lower 

 Mississippi River. References to such rivers as the Wabash 

 and Mississippi are to the parts that border Illinois. For 

 example, lower Alississippi refers to that part of the Mis- 

 sissippi River between the mouths of the Missouri and 

 Ohio rivers (Fig. 2). For species known in Illinois from 

 only one or a few records, the name of the stream and 

 county involved are usually given, and attention is called 



to the need for substantiating records. Drainage bound- 

 aries and some of the principal streams of the state are 

 depicted in Fig. 2. 



Statements concerning range are, for the most part, 

 based on material collected since 1950 and deposited in 

 the Illinois Natural Histor)' Survey collections. The state- 

 ments are meant to give what I believe to be the current 

 distribution of the species in the state. Comments on 

 habitat are given for certain species rather rigidly restricted 

 to certain types of water, but no attempt has been made 

 to describe habitats for most of the species. 



A list of more than 30 problematical species is included 

 in this report. The annotations for these species, all hypo- 

 thetical in the Illinois fauna, are self-explanatory. For the 

 most part, the list includes fishes presumably extirpated 

 or at least those that have not been collected in Illinois 

 waters within the past 25 years; old and unsuccessful plant- 

 ings of exotic species that have been recorded in the Illinois 

 literature; recent introductions, the status of which is still 

 unknown; and species known to occur in marginal areas 



Fig. }i. — Location of collections taken. 1950 to date. F.ach 

 dot represents 2 to 50 species of fish from a site. 



