NERVES OF THE DOGFISH 



323 



traced into the midbrain." The relations of the roots of the 

 fifth nerve in Mustelus are essentially as in Squalus. 



Marshall and Spencer ('81), summarizing the studies of other 

 investigators, state for the trigeminal nerve in adult selachians 



-prt.Vil 



Fig. 23 A projection upon the sagittal plane of the roots and ganglia of the 

 V-VII-VIII nervj complex of Mustelus californicus. Left view. X20. 



two roots: 1) an anterior one [portio minor] arising from the 

 brain by two non-ganglionated rootlets; 2) a posterior ganglion- 

 ated root [portio major]. Van Valkenburg's more recent descrip- 

 tion of the roots of the trigeminus in Scyllium ('11a and b) indi- 

 cates that the roots of the fifth nerve in that form are essentially 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 31, NO T) 



