No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 743 
The main ganglion is in young larvae imperfectly separated 
into three parts or regions, an anterior and upper, a median, 
and a posterior one. 
The anterior and upper of these three portions of the gan- 
glion is connected with the brain by the anterior, or trigeminal, 
root of the ganglion. This root arises from the anterior and 
lateral edge of the medulla, and is there distinctly double, its 
dorsal and posterior portion arising superficially in the brain, 
its ventral and anterior portion deeper in the brain, in part 
from the posterior longitudinal fasciculus. These latter fibres, 
which are the motor fibres of the root, either alone or with 
other of the deeper fibres, traverse the anterior part of the 
main ganglion as its anterior commissure, and enter the 
truncus maxillaris trigemini. 
The median and posterior portions of the main ganglion are 
connected with the brain by the posterior, or facial, root of the 
ganglion, which arises from the lateral surface of the medulla 
in front of, and close to, the root of the nervus acusticus. 
It arises as two bundles, which immediately receive a third 
bundle coming from the root of the ganglion of the buccalis 
and ophthalmicus facialis. The anterior of the two bundles of 
the root proper arises at a high level in the brain, apparently 
from the fasciculus communis tract, and enters mainly or 
entirely into the median portion of the main ganglion. The 
posterior of the two bundles arises deep in the brain, and con- 
tains the motor fibres of the root. It enters the posterior 
portion of the main ganglion, and, with the third bundle, 
traverses it as its posterior commissure. The third bundle 
contains the lateral, or sense-organ, elements of the root. 
The root of the ganglion of the buccalis and ophthalmicus 
facialis is the lateral or sense-organ root of the ganglionic 
complex. It arises from a slight swelling on the lateral surface 
of the medulla, close to, and almost as a part of, the root of the 
nervus acusticus. The branch of this root that is sent to the 
posterior root of the main ganglion, may arise as a separate 
root or bundle. 
14. The rami ophthalmicus superficialis and buccalis facialis 
arise from their own special ganglion; the ramus oticus facialis 
