346 H. W. NORRIS AND SALLY P. HUGHES 



In Mustelus there is a large posterodorsal extension of the 

 buccal ganglion within the orbit, from which a number of small 

 nerves emerge, one of which, from its distribution to the poste- 

 rior horizontal portion of the infraorbital canal, Allis correctly 

 considers as the equivalent of the ramus oticus. The rest of the 

 small nerves from the otic portion of the ganglion supply the 

 postorbital section of the infraorbital canal and the spiracular 

 organ which in Squalus is innervated by the ramus oticus proper. 

 In Mustelus the hyomandibular trunk does not lie in a canal in 

 the ventral wall of the ear capsule, but in the ventral portion of 

 the orbit. The ganglion of the ramus mandibularis externus 

 VII is not such a long slender column of cells as "in Squalus, 

 confined to the narrow hyomandibular canal, but lying free in 

 the ventral part of the orbit assumes a more globular form (figs. 

 23 and 37, gmde). 



2. The roots and ganglia of the facialis proper 



The geniculate ganglion is situated upon the hyomandibular 

 trunk in the larger proximal part of the hyomandibular canal, in 

 the cranial wall ventral to the vestibular portion of the ear (figs. 

 17, 24, and 33, ggen.). The geniculate ganglion is everywhere 

 distinct from other ganglia, even where in contact with them. 

 From the ganglion proximally the visceral sensory root fibers, 

 accompanied by groups of motor fibers, pass into the cranial 

 cavity, and curving around the anterior ventral border of the 

 auditory ganglion, between its cells and the root of the ventral 

 lateral-line ganglion, enter the medulla and pass directly to the 

 visceral sensory column in the latter (figs. 12 to 14, 26 to 29, 

 31, 32, and 36, VII rvs.). The slightly medullated character 

 of its fibers renders them especially easy to distinguish from other 

 fiber tracts. The motor root passes through the brain sub- 

 stance immediately ventral to the sensory fibers, from the periph- 

 ery to the lateral motor column. Some of the motor root fibers 

 have the appearance of arising in the ventral motor column. 

 Within the brain the sensory root divides, one part passing 

 directly into the visceral lobe, there to curve posteriorly along 







