[387] 
ALIMENTARY CANAL, LIVER, PANCREAS, 
AND AIR-BLADDER OF AMIURUS CATUS. 
BY A. B. MACALLUM, B.A. 
(Read before the Canadian Institute, April the 5th, 188%4.] 
THE ALIMENTARY CANAL. 
COARSE ANATOMY. 
The cavity of the mouth is very capacious. Its entrance is guarded 
by plates of teeth situated on the maxillaries above and on the 
mandibles below. These are the only regions of the mouth where 
teeth are found. In front of them above and below along the 
margin of the mouth portions of skin, frequently pale or discolored, 
are transitional between the outer skin and the membrane of the 
mouth, and function as lips. 
Behind the pads of teeth and running concentrically with them 
are folds, one above and one below, arising from a relaxation of the 
lining membrane ; that behind the maxille is largest, but both may 
be absent. In one specimen of Amiurus nigricans, the fold reached 
downward and backward into the cavity of the mouth fully one-half 
inch. 
The lining membrane of the mouth is generally colorless. That 
of the sunken palate may have a dark color. When hardened the 
membrane shows minute blotches on a white ground, caused by 
beaker organs (taste-buds !; and the vascular papillze of the subjacent 
tissue. 
The ‘tongue’ is most distinctly observable when the hyoid bone 
is pushed up by the finger from below, and is then an oblong flat- 
tened elevation. A ridge or rather a row of papille runs medially 
over its surface backward into the pharynx. This is the seat of 
numerous beaker organs, especially in the young cat-fish. 
The palate is sunk from the maxille and is divided into two 
shallow depressions by the parasphenoid. 
The surface of the pharyngeal floor anteriorly inclines on each 
side somewhat toward the base of the gill arches. 
