No.3.] ZUSCLES AND NERVES IN AMIA CALVA. 553 
in most of the specimens examined, double, arising by one head 
from the under surface of the posterior extremity of the antorbi- 
tal bone, and by the other from the anterior and under face of 
the prefrontal process this process being pyramidal in shape, as 
described by Sagemehl (No. 104). Where the muscle was single 
in its origin it arose entirely from the antorbital, and in speci- 
mens of about 20 mm. in length it had apparently this origin 
only. Where it has a partial insertion on the antorbital, it 
must, in contracting, depress that bone and so diminish the 
size of the nasal cavity, thus having some functional connection 
with the nose. 
Immediately posterior to the insertion of this muscle a 
strong ligament arises from the outer edge of the ectoptery- 
goid. It runs backward closely attached to the inner surface of 
the loose dermal fold that extends from the edge of the pala- 
tine arch to the maxilla, and which may be called the supra- 
maxillary fold (No. 3, p. 489, and Fig. 20), and disappears on 
the under surface of the dermis behind the superficial fold or 
crease that marks the hind edge of the mandible, its fibres 
running downward and backward somewhat parallel to that 
crease. Another ligament arises from the under surface of 
the anterior of the two infraorbital bones, and running back- 
ward and downward closely attached, as the preceding one is, 
to the dermis between the maxilla and the palatine arch, dis- 
appears on the under surface of the dermis behind the hind 
margin of the mandible and behind the first ligament. 
The third division of the muscle, Zms3, arises in full-grown 
fishes immediately behind the antorbital process from the upper 
surface of the palatine bone near its hind edge. In nearly all 
the fishes examined some of the lateral and upper fibres of the 
muscle continued forward above and across the ligament that 
binds the palatine arch to the prefrontal ossification, and had 
their origin on the posterior face of that bone. The muscle is 
a long one, of flat oval section. It runs downward, outward, 
and backward along the upper surface of the palatine arch 
until it reaches the angle or bend in the upper surface of the 
metapterygoid, where it turns downward and contracts abruptly 
into a long, slender tendon. This tendon continues downward 
