ex FISHES or ILLINOIS 



which the characteristic species of adja'cent areas can not enter, 

 or in which they can not permanently remain. 



DSTRIBUTION CHIEFLY IN THE OHIO DRAINAGE 



Brindled stonecat Pirate-perch 



Green-sided darter Notropis illecebrosus 



Boleichthys fusiformis Ericymba buccata 



Chub-sucker Long-eared sunfish 



DISTRIBUTION CHIEFLY IN THE MISSSSIPPI DRAINAGE 



Short-nosed gar White bass 



Stonecat Yellow bass 



Lake carp Common bullhead 



Notropis cayuga Short-headed red-horse 



Spot-tailed minnow Red-bellied dace 



Notropis rubrifrons Notropis gilberti 



Spotted shiner Long-nosed gar 



Pike Dogfish 



Menona top-minnow Mongrel buffalo 



Trout-perch Black-head minnow 



Pumpkinseed Hybognathus nubUa 



Sauger Redfin 



Yellow perch Rock bass 

 Banded darter 



BOUNDARY BETWEEN NORTHERN AND SOUTHERN SPECIES 



Recurring next to the distinction made on another page 

 (ciii) between northern and southern fishes whose areas ex- 

 tend into IH'nois but not beyond, and comparing the distribution 

 of these groups within the state, as given on Map CIII., we see 

 that northern and southern species meet and mingle in the 

 western part of the state from Meredosia to Pekin on the Illinois, 

 and from Quincy to Dallas City on the Mississippi, but that in 

 eastern Illinois they are separated by a wide interval extending 

 from Cook county to the mouth of the Embarras, in which 

 interval we have never taken any representative of either group. 



The distinctively southern species, although most abundant 

 south of the line 28 "30", nevertheless go up the Waba h to the 

 Embarras, up the Kaskaskia to Shelby county, up the Mississippi 

 to Henderson county, and up the Illinois to Pekin, also following 

 the branches of the Sangamon to Logan county. The northern 

 species, on the other hand, although most abundant above 

 40 20", come down the Illinois to Meredosia, and down the 

 Mississippi to Quincy. 



The boundary between the northern and southern species 

 thus appears as a broad belt some fifty miles in width, extending 

 two thirds of the way across the state just about its center, but 



