The Cranial Nerve Components of Petromyzon. 159 
the most dorsal of the complex. The relative position of the several 
roots is better shown in Figs. 4 and 5 than in the plate. 
The neuromast roots have no connection with the intra-capsular 
ganglion, but run in a compact bundle down over the cephalie and 
mesial face of this ganglion and through the foramen in the floor 
of the capsule close to the mesial angle. As the bundle descends 
past the intra-capsular ganglion it is imbedded in the fibrous membrane 
which celoses the fenestra in the mesial wall of the cartilaginous 
capsule and is closely erowded with other nerve fibers as it passes 
through the foramen. Beneath 
the foramen these fibers enter Fig. 5. 
the second ganglion mentioned. 
The large bundle of fibers emer- 
ges from the foramen at 357, 
is flattened between the capsule 
and the underlying muscle, runs 
ventro-laterally and in 355 joins 
the ganglion which extends 
forward to 343. The ganglion 
spreads mesially in its cephalie 
part, is saucer-shaped to accom- 
modate itself to the auditory 
capsule, and is composed of 
large cells irregularly disposed. 
A bundle of fibers runs 
forward through the mesial 
part of this ganglion and as 
the ganglion ceases fibers from 
its whole cephalie border 
continue forward beneath the 
auditory eapsule forming a thin 
lamina, thinnest at its lateral border but having a thicker bundle 
at its mesial border. At 338 ganglion cells appear and the 
bundle immediately emerges from beneath the cephalie end of tlıe 
auditory capsule as a large ganglion which fills the space between 
the capsule and the trigeminus ganglion. The ganglion is pressed 
against the ventro-cephalic surface of the capsule, to which it 
conforms, and extends forward somewhat between the trigeminus 
ganglion and the eranium. Its cells are moderately large but smaller 
than those of the trigeminus ganglion. 
