6l2 'Journal of Comparative Neurology and Psychology. 



was published. In Scyllium canicula the course of the radix mesen- 

 cephalica through the ccrebelhun was somewhat complex and I sug- 

 gested that this accounted for Edinger's mistaking this bundle for a 

 tractus tecto-cerebellaris. In Scyllium stellare the course of the 

 bundle is identical Avith that in S. canicula except that it makes a 

 much less complex bend or loop in passing through the cerebellum 

 into the velum medullare anterius. The course of the l)undle is so 

 direct that there is no chance of losing or mistaking it in following it 



Fig. 11. Acipeiiser riibicundiis ; some cells of the nucleus tecti as seeu in a 

 transverse section. The bundle of fibers is the beginning of tlie radix niesen- 

 cephalica. X ^'^^• 



through transverse sections. The same is true of Squalus acanthias. 

 Also, in sagittal sections of Scyllium stellare the whole course of the 

 bundle is very clearly followed (Figs. 9 and 10). The way in 

 which the mesencephalic bundle crosses the motor root bundles in 

 these sagittal sections makes it quite impossible to make any mistake 

 as to wdiich root the mesencephalic bundle enters. 



In Acipenser the bundle was previously followed only into the 

 tectum, not to its cells of origin. I have since traced the bundle in 



