No. 3.] LATERAL LINE OF AMIA. 475 
the bone. Trunk 3 runs forward and outward, and lies so far for- 
ward that it is not entirely inclosed in bone, leaving the canal 
between the ethmoid and antorbital, giving off no branches 
in the bone. Trunk 4 is directed downward, forward, and 
outward, and has a single large opening at the surface of the 
bone. Trunks 5 and 6 are given off almost at the same point, 
but on opposite sides of the canal, just before or at the horizontal 
bend in it. Trunk 5 is short, and is directed outward and down- 
ward, It sends one long branch forward with two single and 
one double opening, and one branch outward and downward 
which has two short branches with five openings, making in all 
seven single and one double opening in the system, all lying 
along the lower outer edge of the bone. Trunk 6 is a direct 
continuation upward and backward of the antorbital part of 
the main canal, and is comparatively long, extending from the 
bend in the canal to a point beyond the upper posterior margin 
of the bone and a little in front of the posterior nasal aperture. 
Here it runs directly into, and is continuous with, trunk 4 
supra-orbital, the two trunks or some of their branches meeting 
and anastomosing, and so forming a direct connection between 
the two canals. 
Trunk 6, infra-orbital, after leaving the antorbital bone at its 
hind end, enters the little strip of dermal tissue (near the lateral 
edge of which the posterior naris lies), which extends across the 
top of the head between the lachrymals, and between the frontals 
behind and the nasals and antorbitals in front. The canals that 
traverse this strip of dermis lie in a deeper, denser stratum 
of the corium, which corresponds in position to that of the 
dermal bones in other places. Trunk 4 supra-orbital lies en- 
tirely in this tissue, as does also 6 infra-orbital after leaving the 
antorbital bone at its upper end. This latter trunk usually 
sends one or more creeper-like branches forward, toward or into 
the hind margin of the nasal, and one or more backward, 
toward the median or anterior edge of the posterior nasal aper- 
ture; but these branches are given off so near the point of 
anastomosis that it is often difficult to determine to which one 
of the systems they belong. In the two systems combined, in 
the specimen used for illustration, there were on one side of the 
head twenty-six pores, and on the other twenty-seven, three on 
one side and five on the other being in the nasal. 
