390 PROCEEDINGS OF THE CANADIAN INSTITUTE. 
From the ccecum a fold of the left portion of the mesentery passes 
to the larger loops of the midgut. 
The air-bladder is covered by a peritoneal plate arising from the 
lateral walls of the body cavity and meeting in the middle line. To 
the walls of the air-bladder it is less closely applied than elsewhere. 
Large pellets of fat are distributed in the mesentery, most 
frequently in the fold connecting the cecum and midgut. 
The mesentery is not always continuous, there frequently appear- 
ing in it large, clear spaces, the positions of which are, however, 
irregular. 
The following table of measurements of the intestinal tract, in- 
cludes those of one specimen of A. catus and two of dA. nigricans. 
The length of the body, as here given, is from the termination of 
the snout to the base of the caudal fin. It will be seen from 
examination that the lengths of the same parts in the three are not 
relatively proportional. For instance, in A. catus the length of the 
midgut is 1:25 times that of the body, while in the smaller specimen 
of A. nigricans it is 1:14, and in the larger 1°8. In the numerous 
measurements that I have made of the intestinal tract of cat-fishes 
of various sizes, it was observed that with the increase in body 
length there is more than a corresponding increase in the various 
parts, and especially so in the midgut. The whole intestine also 
from the commencement of the cesophagus to the vent varies from 
1-5 to 2°3 times the length of the body. 
. 2 
: gz I = 
C g | ro Veen . a A 
ZB 2 |Sa3| 3 8 e a a 
a8 BS \a fi = a ea 4 
c oh | 
PAPC OLUUS ls ons) aYors oo ei 31 3°5 Sel ete 40 5 10 55 
A. nigricans (1)...., 38 | 22| 2 | 15 | 32 | 48 | 75) 38 
| | 
A. nigricans (2)....: 60 | 5 eS) 110 9 — 
FINE ANATOMY. 
MOUTH AND PHARYNX. 
The mucous membranes of the mouth and pharynx are exceedingly 
similar in structure, so that the following description applies justly 
