No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 733 
of the ventral end of the seventh septum there was a small 
piece of septum and a small muscle pocket which doubtless 
represented the missing sixth segment. 
The ventral branches (ocv and spv, Figs. 33, 34, and 57, 
Pls. XXVIII and XXXV) of the four occipital and first spinal 
nerves come to the outer surface of the trunk muscles poste- 
rior to the segments to which they belong, and vary greatly in 
their points of exit. The ventral branch of the first occipital 
nerve is a very delicate nerve which usually issues at, or imme- 
diately behind, the third septum. It always joins and fuses 
with the ventral branch of the second occipital nerve, which 
issues from the fourth segment or at the fourth septum. The two 
nerves united join the ventral branch of the third occipital nerve, 
which issues between the fourth and fifth septa; and the nerve 
or trunk so formed sends a communicating branch to the ven- 
tral branch of the fourth occipital nerve. It then turns down- 
ward and forward, behind the hind end of the visceral arches, 
along the anterior surface of the ventral portion of the trunk 
muscles, and near the inner, anterior edge of the clavicle. 
It passes internal to both the pharyngo-claviculares, and 
reaches the dorsal surface of the sternohyoideus near the 
median line of the body. It there gives off several cutaneous 
or general branches, and, continuing forward, sends branches 
first to the middle, and then to the anterior, divisions of the 
sternohyoideus, and ends in a delicate branch which innervates 
the branchiomandibularis. 
In one specimen, and on one side only of that specimen, a 
large branch was found which arose from the third occipital 
nerve, and passed dorsal to, that is, internal to, the second 
occipital nerve. There it received an anastomosing branch 
from that nerve, and then ran outward and upward internal to 
the nervus lineae lateralis. As the specimen had been cut, in 
dissection, above that point, the ultimate destination of the 
nerve could not be determined. Nothing anything like it was 
found in any other fish, and I can only think that it was some 
marked irregularity due to accident of some kind. 
The ventral branch of the fourth occipital nerve issues, 
as it should, in its own segment, the fifth, along the anterior 
