ee 
Bs 
The carp, Cyprinus carpio L., furnished the largest 
series of returns. In Table V, p. 18, the 37 carp returns are 
divided into five convenient time periods and the migration constant 
is calculated for each. In contrast with the similarity of these 
calculated migration constants, the average distance per day varies 
widely, as may be seen in the last column, 
Since the number of returns on other single species of fish 
is insufficient for statistical uses, I have lumped the data from 
all of the basses, crappies, and sunfishes—the so-called "fine fish." 
It may be seen in Table I that all of these have similar calculated 
rates of migration. These data have been arranged in three different 
time periods in Table VI, p. 19, where it may be seen that the cal- 
culated migration constants are more uniform than the average 
distances pcr day. 
To determine whether fishes of different sizes migrate at 
different rates, the 37 returns from carp, which ranged from 1 to 5g 
pounds, have been divided, in Table VII, p. 20, into four weight 
classes. The migration constants for these four weight classes vary 
from 0.25 to 0.66 but it is not considered that these numbers indi- 
cate any real differences in rate of movement between carp of 
different sizes. 
In Table VIII, p. 20, these 37 carp have been divided 
according to streams, and migration constants calculated. The data 
on some of these streams are too fragmentary to be of much signifi- 
cance, but the returns from Fox River carp are sufficiently complete, 
and diverge from those of other streams so widely, that it seems 
certain that carp do migrate shorter distances there than in other 
streams. The reason for this lack of extensive migration in the 
Fox River is obvious since it is crossed at many points between 
McHenry and the mouth by dams. These dams are high enough to prevent 
fish going upstream at any time except during very high floods, and 
from going downstream, unless they go through the turbines or over 
the tops of the dams at flood stage. Furthermore the river was so 
low throughout 19350 and the years succecding that carp are for the 
most part restricted to the pools immediately above these dams. 
For 15 years the carp of the upper and middle Illinois 
River have exhibited an unusual abnormality referred to by local 
fishermen as "knothead" carp. We have learned that the knothead 
abnormality is caused during the early life of the carp by certain 
pollutional conditions which existed in the Illinois River. In the 
winter of 1926-27 when a detailed study of the knothead abnormality 
was made in the Illinois River, it was found that approximately 90 
per cent of the carp from Feoria Lake and points upstream showed 
abnormality in greater or smaller degrees. 
