IOWA ACADEMY OF SCIENCES. 
97 
trunk some of its fibers are given off to the digastric 
muscle. Posteriorly it apparently distributes fibres to the 
dorsotrachealis muscle, but of the certainty of this I have 
not been able to satisfy myself. Posteriorly its relation to 
the dorsal series of lateral line sense-organs is such as to 
make it not improbable that it is concerned with the 
innervation of these structures. The nerve runs at the 
extreme lateral border of the longissimus dorsi muscle just 
beneath the lateral line sense-organs. Unfortunately the 
nature of my preparations does not permit me to trace 
fibers from the nerve to the sense-organs, but I find in 
many instances that as a sense-organ is approached the 
nerve bends out to the extreme border of the muscle until 
it lies close against the sense-organ, then after passing the 
sense organ sinks back to its former level. Posteriorly 
when the nerve leaves the muscle its fibers may be seen 
running along almost in direct contact with the sense- 
organs. The sense-organs continue nearly to the tip of 
the tail, but I have been unable to trace the nerve pos- 
terior to the pelvis. The nerve bears the same relation in 
position to the dorsal sense-organs that the ramus lateralis 
inferior of the vagus nerve does to the ventral series of 
sense-organs, only more intimate. 
The suggestion of the presence of lateralis fibers in a 
branch of the hyomandibular trunk of the seventh cranial 
nerve is so contrary to accepted opinions that one may 
well hesitate to advance the possibility. But this entire 
so-called dorsotrachealis branch is an anomaly, apparently 
without a homologue. I have been unable to trace any 
connection between either the ramus superior or the ramus 
medius of the vagus and the lateral line organs. Neither 
do I find any communications between this facial branch 
and any branch of the vagus. 
In the light of these facts this nerve evidently should 
not be termed the dorsotrachealis branch, but more fittingly 
the ramus lateralis posterior of the seventh cranial nerve. 
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