No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 697 
internal to the fourth and fifth levators, and dorsal to, and 
then posterior to, the posterior of the two upper ends of the 
efferent artery of the fourth arch. Behind that artery and 
behind the hind end of the fifth ceratobranchial, the ramus 
posttrematicus turns downward, sends a branch to the adductor 
muscle of the fifth arch, and then runs forward and median- 
ward along the ventral surface of the fifth ceratobranchial. It 
crosses the lateral end of the transversus ventralis posterior, 
sends branches to that muscle, and then to the pharyngo- 
claviculares externus and internus, and ends in several delicate 
branches, which enter the tissues near the basal line. McMur- 
rich says (No. 76, p. 138) that the claviculares in Amia are 
innervated by branches from the first spinal nerve. This is 
an error due, doubtless, to the fact that the fourth occipital 
nerve, mistaken by him for the first spinal, sometimes enters, 
but simply transverses, or gives off a branch which transverses, 
the inner of the two muscles. The nerve does not innervate 
the muscle; it simply perforates it. 
The ramus pharyngeus inferior (fzv+) turns downward at 
the hind end of the branchial apparatus, then medianward, and 
separating usually into two main portions, sends branches 
forward and backward along the outer surface of, and into, 
the constrictor oesophagei. 
The truncus pharyngeus superior is the median and posterior 
of the two divisions of the median and posterior of the two 
main nerves that arise from the fourth vagus ganglion. It runs 
medianward, backward, and downward toward the front end of 
the oesophagus, where it turns directly medianward ventral to 
the efferent artery of the third and fourth arches, and passes 
between the transversus dorsalis posterior and the retractor arc. 
branch. dorsalis. It then turns forward and medianward toward, 
and then along, the median edge of the third infrapharyngo- 
branchial, sending in its course some branches through that 
element, the branches perforating first the transversus posterior, 
or the anterior end of the constrictor oesophagei. It is distrib- 
uted mainly, if not entirely, to dermal tissues near the hind and 
median edge of the pharyngeal bone. On the left-hand side 
of the specimen used for Fig. 52, a branch of this nerve 
