The Cranial Nerve Components of Petromyzon. 165 
is imbedded in the membrane (425). In 430—432 a ganglion appears 
in connection with roots 2 and 3, which continues to 448. This is the 
ganglion of the glossopharyngeus (Figs. 7—11). 
Root 4 arises between sections 414 and 420. It is formed of 
fine fiberss which eome down the lobus vagi through the spinal 
Vi tract and its nucleus, and ofa small strand of motor fibers from 
the lateral motor column which joins the root just as it leaves the 
surface of the brain (420). It is possible that general cutaneous 
fibers from the spinal V!E tract enter this root, but I can not de- 
monstrate them with certainty. In 423 the root stretehes from the 
brain to the eranium. In the same section root 5 of fibers from the 
lateral motor column runs parallel with it, and at 430 they enter 
the eranial membrane together, ventro-mesial to root /. They pass 
through in 432 and in 434 root 6, also motor, follows them closely, 
running direetly latero-ventrad from its point of origin. At 440 arises 
root 7, consisting of motor fibers and probably also faseiculus communis 
fibers. Since the latter are somewhat doubtful they are not shown 
in the reconstruction. It passes rapidly through the eranium follow- 
ing, root 6 (Fig. 9, 10, 11). At this point (441) the several roots have 
the following disposition (Fig. 12): latero-ventrally the ganglion of 
roots 2 and 3, growing smaller; dorso-mesially to it roots /6 and 
Morpholog. Jahrbuch. 34, 12 
