476 LANDACRE AND McLELLAN 
of the general visceral ganglion, each branchial nerve arising from 
a ventral prolongation extending downwards towards the appro- 
priate gill. The condition shown by Herrick (’99, text-fig. 5) 
gives the exact relation of these branchial ganglia in Lepidosteus 
and Ameiurus, with the exception that the branchial ganglia are 
a little larger and somewhat more detached than in Ameiurus 
and Lepidosteus and the general visceral portion seems to be 
smaller. In the frog there are only two large branchial nerves 
and they both arise from the same ganglion. This ganglion has 
the same appearance and morphological relations as Branchia] X! 
of Lepidosteus (Landacre 712). The question arises whether the 
branchial ganglion of the frog represents the branchial X! of 
Lepidosteus, Ameiurus and Menidia or whether it represents 
two or more branchial ganglia of these types fused. The question 
can be answered definitely only by careful study of the embryo- 
logical development of the branchial ganglia and nerves. The 
condition in the ganoid (Landacre 712) indicates that branchial - 
ganglia other than X! are incorporated with the general visceral 
X, since these ganglia are much smaller than in Menidia and much 
less distinct. The behavior of the second branchial nerve arising 
from this ganglion, as will be shown later, indicates that the gan- 
glion that we have called visceralis X? really represents the general 
visceral X of Lepidosteus plus one or more branchial ganglia 
and that the branchial ganglia of X (figs. 1 and 2, G.V.X') repre- 
sents principally branchialis X! of Lepidosteus. 
As mentioned above, there are two branchial nerves (figs. 1 and 
2, Br.X* and Br.X?) arising from branchialis X. These corre- 
spond to the rami branchialis (6) and (7) of Strong’s plot. The 
anterior (6 of Strong’s plot) arises from the extreme anterior end 
of the ganglion and pursues a course downward and forward to 
the gill. The second (7 of Strong’s plot) arises toward the poste- 
rior end of the ganglion and runs downward and forward to the 
gill. This nerve on entering the ganglion, however, is not lost 
entirely among the ganglion cells, as is the first nerve, but pur- 
sues a course backward on the under surface of branchial X until 
it reaches the anterior border of visceral X. It is, however, in 
its course diminished in size and it may be possible that some of 
