Johnston, The Radix MesencephaUca Trigemini. 6ii 



or deep decussation of the cerebellum. This decussation in all sub- 

 mammalian forms studied is the commissure of the nucleus visceralis 

 cerebelli (secondary gustatory nucleus). The radix also runs beneath 

 the tractus tecto-cerebellaris, which I have identified in the selachians, 



Fig. 10. Three sections from the same series as those drawn iu Fig, 9, but 

 farther laterad. Only the mesencephalic bundle and its immediate surround- 

 ings are drawn. At D it comes into contact with the bundles of the motor 

 root of the trigeminus, at E it is passing beyond the motor bundles, at F it 

 joins the tractus spinalis trigemini to form the sensory root. The mesen- 

 cephalic bundle crosses the motor Ijundles nearly at right angles and there is 

 no indication of interchange of fibers. X ^^• 



Acipenser, and the mammals studied including the human embryos. 

 The course of the bundle in Scyllium canicula, Acipenser and tec- 

 tums was described in my previous paper. I wish to make certain 

 additional notes on the basis of preparations made since that paper 



