Kappers, Teleostean and Selachian Brain. 77 



ascendens. This tract, having received not a single fiber of the 

 trigeminus, goes forward or upward, so that I must deny the pres- 

 ence of the mesencephahc root, as Johnston and Kingsbury did. 

 These arguments seem to me sufficient for denying the presence 

 of this radix in Gadus and Lophius, and also the direct cerebellar 

 trigeminus root of Haller, Edinger and Johnston. 



Immediately caudad of the entrance of the nervus trigeminus 

 compact bundles of medullated fibers which at first were situated 

 dorsally of this nerve (Fig. xci) go in a ventral direction along the 

 outer border of the oblongata. These are bundles which origi- 

 nated in the cerebellum farther forward. Between the trigeminus 

 and the first roots of the facialis they pass to the ventral side of the 

 oblongata where, somewhat farther caudad, they take the place 

 formerly occupied by the tr. tecto-bulbaris et spinalis, the latter 

 having partly terminated and partly turned more medially. In 

 this situation they go farther caudad (Figs, xciii to xcix) giving off 

 successive bundles into the nuclei situated more dorsally, these 

 bundles decussating to form part of the fibrae arcuatae externae. 

 They disappear behind the vagus region. 



Edinger also mentions a tr. cerehello-spinahs ventralis in the 

 selachians and considers it to be a connection between the sensory 

 nuclei and the cerebellum, while Banchi traced its fibers down into 

 the spinal cord. Haller, on the contrary, describes this same 

 tract in Salmo as descending into the trigeminus region and going 

 to the motor columns. Johnston also describes the tr. cerebello- 

 spinalis ventralis, as far as its origin and early course are con- 

 cerned, in the same way for Acipenser; but although he worked 

 with GoLGi preparations, he could not be sure about its termina- 

 tion; which perhaps is due to the fact that he did not see its con- 

 nection with the fibrae arcuatae externae which he explains in 

 another way. 



There are still other cerebellar fibers to be mentioned in the 

 post-trigeminal region. These are bundles connecting sensory 

 centers with the cerebellum. A considerable tract must be con- 

 sidered as belonging to this system which descends along the outer 

 side of the cerebellum and after a short course ends in the posterior 

 part of the nucleus lateralis cerebelli behind the end of the second- 

 ary communis tract (Fig. Ixxxvii, Plate VI, marked S4-^)- ^^^ 

 the fibers which probably belong to the same category destined for 

 centers farther caudad (chiefly for the static centers, in my opinion. 



