36 
BUIvLETIN of the bureau of fisheries. 
the smooth dogfish (Musielus canis), and the killifish {Fundulus heteroclitus) . The 
work on Ameiurus and Fundtdus was done by G. H. Parker, that on Mtistelus by R. E. 
Sheldon. 
EXPERIMENTS WITH AMEIURUS. 
Ameiurus nebulosus is a bottom -feeding fish possessing fair powers of sight and 
unusual gustatory organs located not only in the mouth and on the general outer surface 
of the body, but especially on the eight barblets about the mouth (Herrick, 1903). It 
is a hardy fish, living well in confinement and undergoing operations with success. It 
possesses near its anterior end a pair of nasal chambers, each of which is provided with 
two apertures, one anterior, the other posterior. The anterior aperture is nearly cir- 
cular in outline and is located on a slight conical elevation somewhat anterior to the 
root of the dorsal barblet. The posterior aperture is slit-like in form and lies imme- 
diately posterior to the same barblet. The anterior aperture is apparently always open; 
the posterior one seems capable of slight closure, but is usually freely open. 
By keeping eatfishes a few days without food they can be made most eager for it, 
and if into an assemblage of such individuals a few fragments of fresh earthworms are 
dropped, the excitement that ensues will last some time after the final piece of worm 
has been swallowed. During this period the fishes swim about actively in the lower 
part of the aquarium, now in this direction, now in that, and frequently sweep the bot- 
com with their barblets. As can be noticed when feeding actually occurs, the fishes 
seldom seize a fragment of worm until their barblets have come in contact with it. 
Yet before they have thus touched any food they show a marked degree of excitement 
and it is this initial nervous state that would lead an observer to suspect that they 
scented their food. This phase of their activity was, therefore, taken as the one to be 
tested in connection with their olfactory organs. 
The nasal chambers of the catfish contain ciliated epithelium, the action of which is 
to draw water in at the anterior olfactory opening and diseharge it at the posterior one. 
As can be demonstrated with carmine suspended in water, the passage through the 
chamber is afccomplished in 8 to 10 seconds. 
As a preliminary step in testing the eatfishes, five normal fishes were placed in a 
large aquarium over night that they might become accustomed to their surroundings. 
In this aquarium were then hung two wads of cheesecloth, in one of which was con- 
cealed some minced earthworm. The fishes, which were swimming about near these 
wads, were then watched for an hour and their reactions in reference to the wads were 
reeorded. The wad without worms was passed by the fishes many times and did not 
excite any noticeable reaction. The wad containing the worms w^as seized and tugged 
at eleven times in the course of the hour, notwithstanding the faet that from time to 
time this and the other wad were interehanged in position. Not only did the fishes 
thus openly seize this wad, but when in its neighborhood they would often turn sharply 
as though seeking something without success, a form of reaetion seldom observed near 
the wad which contained no worms. Two other sets, of five normal fishes eaeh, were 
tested in this manner and with similar results. It was perfectly clear to anyone watehing 
