96 
IOWA ACADEMY OF SCIENCES. 
ately enter the digastric muscle. According to Kingsley 
the dorsal one of these breaks up into smaller branches 
supplying this muscle, while the ventral one passes postero- 
ventrally through the muscle. I find that both branches 
give off fibers to the muscle and pass back, uniting into 
one trunk near the posterior border of the muscle. In 
passing between the muscle fasciculi both branches 
become much flattened and in some places difficult to 
follow. 
Krona the posterior border of the muscle the nerve 
rapidly ascends nearly to the dorsal border of the thymus 
gland, along which organ it passes posteriorly, for some 
distance being imbedded in the dorso-lateral border of the 
gland. Before reaching the thymus gland the nerve 
divides, the two divisions reuniting shortly after the gland 
is reached. In some cases a second branch is given off 
shortly before the first branch unites with the main nerve. 
This second branch has been followed to its union with 
the main trunk posterior to the dorsotrachealis muscle. 
In other cases the second division appears not to occur. 
After passing back nearly to the posterior border of the 
thymus gland the nerve enters the extreme posterior part 
of the dorsotrachealis muscle. It possibly gives off some 
fibers to the muscle, but the main trunk continues poster- 
iorly into the connective tissue ventral to the lateral 
border of the longissimus dorsi muscle and between the 
latter and the intertransversales muscles, running approx- 
imately parallel with the ramus lateralis medius of the 
vagus nerve. 
Posteriorly both nerves enter the longissimus dorsi 
muscle and continue within it to the posterior part of 
the body (their ultimate distribution). The facial ramus 
runs near the lateral border of the muscle, in some 
regions just at the border. A short distance anterior 
to the level of the posterior limbs the nerve leaves the 
muscle and runs just beneath the skin. I did not suc- 
ceed in tracing with certainty its fibers posterior to the 
pelvis, but they doubtless run far back in the tail. As to 
the function of this nerve: As it leaves the hyomandibular 
