520 ALLIS. [Vou. II. + 
turns dorsalward, and, lying close beneath the epidermal lining 
of the dorsal side of the gular plate, runs forward dorsal to the 
hind edge of the geniohyoid muscle. Here it turns upward and 
backward, and then immediately upward and forward toward 
the front edge of the hyohyoideus muscle, round which it turns 
upward and backward, and, passing external to the front end 
of the sternohyoid muscle, enters the first branchial arch, and 
joins a part of the main nerve of that arch. This main nerve, so 
far as could be determined, is formed by the union of the post- 
branchial branch of the glossopharyngeal and the prebranchial 
branch of the first vagus ganglion. At the point where it is 
joined by the nerve of the gular line it has just separated into 
two parts, one of which runs downward and inward, and the 
other upward and inward, to be distributed to the tissues on the 
upper surface of the hyoid apparatus. It is this last branch that 
is joined by the nerve of the gular line. 
7. Review of Nerves and Organs. 
Reviewing briefly the arrangement of the nerves and organs, 
there are in front of the double pore 17-17, where the opercu- 
lar and infra-orbital lines unite, sixteen separate canal organs 
or groups of organs along each line. The last two organs 
on each line, Nos. 15 and 16, are supplied by branches of a 
single nerve, which is directed posteriorly along the canal. 
Organs 11 and 12 of each line are also supplied by branches, 
directed anteriorly, of a single nerve; while the intermediate 
organs, Nos. 13 and 14, are in most cases supplied by in- 
dependent branches. On the infra-orbital line a branch of 
the otic, anterior to organ 15, supplies the organ or group of 
organs of the spiracular cleft; while on the opercular line a 
branch of the mandibularis given off next in front of the single 
nerve to organs 1§ and 16, and hence in a corresponding posi- 
tion, supplies the organs of one of the surface lines of the cheek. 
The other cheek line and the surface line on the mandible are 
supplied by a single nerve, which, in one of the two sets of 
sections in which it was traced, arose as a branch of a nerve 
supplying a regular canal organ. The possible significance of 
this will appear in considering the arrangement of the dorsal 
nerves behind the facial. The horizontal cheek line ends close 
