No. 3.] LATERAL LINE OF AMIA. 519 
that canal, it runs outward, backward, and upward, and enters 
the bony canal of the opercular line immediately under organ I5. 
It sends a branch to this organ, and then continuing upward 
inside the bony canal, immediately underneath the epidermal 
lining, ends in organ 16, the last one of the line. Organs 14 
and 13 are supplied by separate branches, given off either 
from the mandibularis externus or from the main ramus man- 
dibularis before it has separated into an external and internal 
portion, Organs 12 and 11 are supplied by a single branch, 
which, as in the case of the branch to organs 15 and 16, enters 
the bony canal under the first organ supplied, No. 12, and then 
passes on inside the canal to the second one, No. 11. Where 
these branches are given off from the main ramus mandibularis 
or the main truncus, it is from that part of the nerve that 
contains the fibres which afterward separate as the externus. 
Beyond the branch to organs 12 and I1, separate branches are 
sent in succession to each organ up to No. 4. The nerve then 
enters the bony canal, and running forward inside it, supplies 
in succession organs 3, 2, and I. 
Between the single branch that supplies organs 15 and 16, 
and the next regular one to organ 14, a branch is sent out- 
ward through the adductor mandibulz muscle and then forward 
along its outer surface, immediately underneath the horizontal 
cheek line, branches being sent in succession to each organ of 
the line. A similar nerve is given off between the branch to 
organ 13 and the one to organs 12 and 11. This nerve also 
passes outward through the adductor muscle, and then for- 
ward along its outer surface, but it soon separates into two 
parts, one of which goes to supply the vertical cheek line, and 
the other the pit line on the mandible. In both cases the 
nerve arrives near the middle of the line it supplies, and there 
separates into two parts which run toward either end of the 
line, sending separate branches to each organ. In one specimen 
the nerve supplying these two pit lines was not given off as a 
separate nerve from the externus, but as a branch from the 
nerve supplying organs 12 and II. 
The innervation of the line of the gular plate could not be 
fully determined. Branches can be traced from the different 
organs of the line to a single nerve which runs backward in- 
ternal to the plate. At the hind edge of the bone the nerve 
