518 ALLIS. (Vou. II. 
or supratemporal branch of the lateral nerve. It is joined soon 
after leaving its ganglion by a branch arising inside the cranial 
cavity, either from the root of the lateral nerve or from the root 
of the vagus, which here contains numerous ganglion cells. 
This branch, although closely applied to the regular dorsal 
nerve, is wholly separate from it. It is distributed entirely to 
the general tissues of this part of the head, including doubtless 
the surface organs, although the direct connection with any of 
them was not determined. 
The next or second regular dorsal branch of the lateral nerve 
is given off near the base of the nerve, and not from the gan- 
glion. It supplies organ 20 infra-orbital and the dorsal pit line 
of the body, branches being sent in succession to each organ 
or series of organs of that line. Other dorsal branches of the 
lateral nerve are then sent in succession to organ 21 infra-orbital 
and the organs of the lateral line of the body. 
The lateral nerve has an undulating course, as shown 
by longitudinal horizontal sections (Fig. 48, Pl. XLI.). Each 
full undulation of the nerve corresponds to a muscle segment, 
and from the outer crests of each the branches sent to the 
organs of the lateral line arise. Running outward along the 
intermuscular septa, they pass through the corium, and then 
backward along the under surface of the scale they supply. 
Reaching the anterior end of the section of canal contained in 
this scale, the nerve enters it through a special passage, and 
supplies the single organ or groups of organs found there in the 
same way that the organs of the head are supplied. Each of 
these nerves, before reaching the under surface of the dermis, 
sends a branch upward and outward through the corium, a little 
dorsal to the point where the main nerve pierces it. Arriving 
under the same scale, this branch runs backward, dorsal to and 
parallel to the main nerve, and, piercing the scale about opposite 
the regular canal organ, supplies the corresponding series of pit 
organs. 
The organs of the operculo-mandibular line are all innervated 
by branches of the R. mandibularis facialis externus. The first 
one of these branches is given off before the externus has 
separated from the main truncus hyoideo-mandibularis facialis. 
Leaving the truncus immediately after its passage from the 
facial canal through the hyomandibular, or even while still in 
