7 
opened, it will be seen that the whole jaw apparatus 
swerves towards the eyeless side. The mechanism by 
which this is effected is described elsewhere. The expla- 
nation of this asymmetry is that the fish must seek its 
food on the sea bottom, and the torsion of the jaws towards 
the under side is hence a physiological convenience, if 
not a necessity. The same consideration explains why the 
teeth, which are blunt and flattened, and not pointed like 
those of the cod, are situated almost entirely on the eyeless 
side. Within the mouth will be seen the maxillary and 
mandibular breathing valves, or “‘ internal lips,” to pre- 
vent the regurgitation of water through the mouth on the 
fall of the gill cover.t The anus is situated very far 
forward in front of the ‘anal spine,” and is a large 
median opening elongated from before backwards. The 
urinary papilla of the female is distinctly on the ocular 
side, a little distance above and behind the anus. The 
oviducal aperture is large and lies immediately behind the 
anus. It is very obvious in the spawning season, but at 
other times of the year we have failed to find it, so that 
it is either occluded then, or very minute. In the imma- 
ture fish we believe it does not exist. In the male the 
papilla is in the same position, but is here a urinogenital 
papilla. We have failed to find any external distinction 
between the two sexes, but the male is smaller than the 
female when it first becomes mature. The pair of anterior 
and posterior nostrils on each side are on the ocular side 
situated between and in front of the two eyes, and on the 
eyeless side in front and to the left of the left eye. 
Between the two eyes and passing backwards there is 
a prominent ridge formed almost entirely by the right 
frontal, and in a line continued back from this ridge are 
¢ Dahlgren, Zool. Bull., 1898. 
