THE EPIBRANCHIAL GANGLIA OF LEPIDOSTEUS 9 
The ventro-lateral lat. is mesial to the geniculate, while it is 
lateral in the Amphibia (Coghill, 702); and lastly the branchial 
ganglia of the X, in contrast with the Amphibia, are fairly dis- 
tinct. 
The branchial ganglia of the 10 mm. embryo are in an inter- 
mediate stage, as stated above, the branchial ganglion of the VII 
being completely formed, or rather detached from the epidermis, 
and the last two branchial ganglia of the X not yet formed owing 
to the absence of the last two gills. The same statement can be 
made of the ganglia as a whole. The V, VII, VIII and IX 
ganglia are definitely outlined, while the posterior portion of 
the X, the visceral portion, is not definitely formed. 
The general visceral and general somatic ganglia which arise 
from the neural crest pass through a stage when their cells are 
quite loosely arranged and their boundaries are indefinite, so 
that, during the early stages in the formation of neural crest 
ganglia it is difficult to determine the exact limits of their bound- 
aries. The general visceral X is in this condition in the 10 mm. 
embryo. If one chooses an older embryo, however, in which 
the X ganglia are fully formed, the V and VII ganglia are fused to 
such an extent that it renders their description difficult unless 
the nerve components are readily separable by differences in 
size. This condition is not reached in a 6-inch Lepidosteus. 
The process of fusing of ganglia is particularly true in the case of 
the lateralis VII and the auditory. There is usually a brief 
period during the growth of these ganglia when their boundaries 
can be made out; but preceding and following this period the 
general visceral VII, lateralis VII, and auditory are likely to be 
more or less fused. 
The profundus ganglion (ganglion mesencephali; trigeminus I) 
This ganglion lies dorsal to the posterior portion of the optic 
vesicle (figs. 1, 4, 5). It is an elongated cord-like mass of cells 
placed diagonally in the mesoderm between the posterior portion 
of the optic vesicle and the mesencephalon. ‘The anterior end 
