‘ No. 3.] LATERAL LINE OF AMIA. 521 
to organ 11 infra-orbital; and the vertical cheek line, close to 
organ II operculo-mandibular. In front of this the canal organs 
on both lines are innervated by separate branches from the 
main nerve of the line. 
Behind the point where the infra-orbital and opercular lines 
unite, organ 17 is supplied by the dorsal branch of the glosso- 
pharyngeal, which also supplies a line of surface organs lying 
dorsal to it. The next dorsal nerve, the first branch of the 
lateral line nerve, supplies organs 19 and 18, the organs of 
the supratemporal commissure, and a line of pit organs dorsal 
in their innervation to all of these. The second branch of 
the lateral nerve supplies organ 20 and the dorsal body line of 
pit organs. The next branch, so far as could be determined, 
supplies organ 21 alone; but each of the following branches 
for nearly the full length of the line normally supplies an 
organ of the lateral line and a corresponding line of pit organs. 
The supratemporal cross-commissure, in the Characinidz 
(No. 13, p. 36), lies in the parietals, and according to Sagemehl 
is an independent formation not to be compared with the com- 
missure in Amia. So far as can be determined from his descrip- 
tion, it occupies about the position of the middle dorsal pit line 
on the head of Amia. If it has the same innervation as this pit 
line, that is by the glossopharyngeal, a not improbable supposi- 
tion, its exceptional position can easily be explained ; for a canal 
line in one form is often represented by a pit line in another, as 
for instance, the anterior commissure in Amia and the corre- 
sponding pit line in Esox or Salvelinus ; and probably also the 
anterior dorsal pit line in Amia and the cross-commissure in 
Mustelus, which has a corresponding position and apparently 
the same innervation. 
In Fierasfer (No. 5, p. 38) the arrangement of the canals in 
this part of the head is markedly different from that in Amia. 
The cross-commissure leaves the main canal near the hind end 
of the squamosal directly opposite the upper end of the opercu- 
lar canal, apparently as a direct continuation of that canal. It 
is innervated by the “ramus ascendente”’ of the lateral nerve, 
a branch which corresponds to or comprehends, according to 
Emory, both the supratemporal (probably of vagus) and opercular 
branches in other fishes. The “ramus ascendente”’ innervates 
not only the organs of the commissure, but also those in the 
