386 
Bluegills (Lepomis pallidws), Wells (715): .........-sc.sscvevsancsees 7.7-7.9 
Bullhead! (Amevrius anetas)) Wells, (C215) ccm wrecteic ates orciereeustatenenene ale erie » 1.47.7 
Crappie (Pomozis annularis), Wells ((15)..............2. cee eeeee sees 7.38-T7.4 
Rock bass (Ambloplites rupestris), Shelford and Allee (’11).......... 18) 
Golden shiner (Abramis crysoleucas), Shelford and Allee (’11)........ Tot 
*pH calculated by Greenfield and Baker equation mentioned on p. 385. 
Lepomis humilis 
Micropterus salmoides 
Micropterus dolomieu 
Ambloplites rupestris 
Abramis crysoleucas 
Lepomis megalotis 
Lepomis cyanellus 
Pimephales notatus 
Notropis whipplii 
Notropis cornutus 
Fic. 1. Showing the range of hydrogen ion concentrations selected 
by ten species of fish (about 12 experiments per species). The actual 
selections are plotted, and a broken line indicates the author’s impression 
as to the probable range in which they would be found. The polygons fall 
approximately in the order of occurrence in swift water. The letters 
indicate occurrence in creeks (C), small rivers (S), and in lakes and 
ponds (L). When two or three letters are used in connection with a 
polygon, the first one indicates the type of water in which the species 
is most numerous, and a single letter signifies that the species is commonly 
found only in that one type of water. 
An EXAMINATION OF CERTAIN ILLINOIS WATERS WITH SPECIAL 
REFERENCE TO HyproGen Ion CONCENTRATION 
A study of fish breeding-grounds was conducted by the author in 
1919-20, and the pH values observed are shown in Table V1; the oxygen, 
in Table VII. There was a marked difference between the carp and 
bass breeding-grounds; in no case were they the same either at the top 
or bottom. The bass breeding-grounds were characterized by clean sand 
bottom; the carp grounds, by dark mud. Table VI shows sharp differ- 
ences in oxygen content at the bottom at all dates on which they were 
examined. 
