536 G. H. Parker 



Evidently^ the nostrils of fishes, like those of the higher verte- 

 brates, are innervated by fibers from the trigeminal nerve, and 

 it is this nervous mechanism rather than the olfactory apparatus 

 that is stimulated by the substances that have ordinarily been 

 applied by experimenters. In fact, so far as the olfactory appar- 

 atus of the fishes and amphibians is concerned, we must agree 

 with Nagel ('94, p. 61) that no one thus far has discovered any- 

 thing positive concerning its function. It is, therefore, a matter 

 of interest to record what seem to be unquestionable reactions 

 dependent upon the olfactory apparatus of our common fresh- 

 water catfish, Amiurus nebulosus. 



Amiurus nebulosus is a bottom-feeding fish possessing fair 

 powers of sight and unusual gustatory organs located not onlv 

 in the mouth and on the general outer surface of the body, but 

 especially on the eight barblets about the mouth (Herrick, '03). 

 It is a hardy fish, livingwell in confinementand undergoing opera- 

 tions 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 

 circular in outline and is located on a slight conical elevation 

 somewhat anterior to the root of the dorsal barblet. The pos- 

 terior aperture is slit-like in form and lies immediately 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 catfishes a few days without food, they can be made 

 most eager for it, and if into an asseniblage 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 excit- 

 edly in the lower part of the aquarium, now in this direction, now 

 in that, and frequently sweep the bottom with their barblets. As 

 can be noticed when the feeding actually occurs, the fishes seldom 

 seize a fragment of worm till 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. 



