918 THE AMERICAN NATURALIST. 
and consequently was not able to make observations on the 
interior of the nest; by reaching back in the hole a distance of 
sixteen to eighteen inches I could feel the egg mass, and upon 
the removal of a portion of the eggs found them to be in late 
cleavage stages, and from previous observations inferred that 
they could not be more than twelve hours old. 
The above fragmentary notes embody, so far as I am aware, 
the first published observations on the behavior of the bullhead 
during the breeding period. They are recorded with the feel- 
ing that they may be of service to those who have so long 
sought the embryological material of this primitive teleost. I 
may further remark that a study of the breeding habits under 
natural conditions shows that Ameiurus rarely burrows in nest- 
ing, but instead seeks concealed places beneath logs, stumps, 
boards, or even pails or other receptacles which are easy of 
access. If, however, a modified environment replaces the 
natural, and the places for concealment be no longer present, 
as in the artificial ponds, we find the fish adapting themselves 
to this changed condition and constructing nests which often 
require two or even three days of unceasing labor to prepare. 
In closing I cannot refrain from suggesting that a more 
extended series of observations would doubtless show that 
other fishes, like Ameiurus, manifest an entirely different 
behavior during the spawning period as a direct adaptation to 
the changed environmental conditions. Indeed, my observa- 
tions on the dogfish (Amia) and the black bass living in the 
ártificial ponds indicate that this is true of these forms as well. 
UNIVERSITY OF CHICAGO. 
VO ee 
