106 ANATOMY OF THE CENTRAL NERVOUS SYSTEM. 



last-named cell-group consists of two large spherical nuclei lying rather far 

 to the posterior aspect, — the nuclei globosi cerebelli (see Fig. 47). They 

 lie so direct in the plane of the nucleo-cerebellar tract and are so completely 

 snrrotinded by the bundles of this tract, that they are probably to be 

 counted in with this tract. In birds, and probably also in reptiles, small 

 masses of cells lie laterally from these: the Nuclei later ales Vermis. In 

 mammals one finds in the same region not only several small nuclei, but 

 quite lateral from this, in the cerebellar hemispheres, a large much-folded 



Fig. 59. — Frontal section througli the midbrain of a shark: Soylliimi oani- 

 cula. Length of body, thirty centimeters. Showing the decussation of the 

 Tractus tegmento-cerebellares. 



nucleus: the Oliva cerebelli or the Nucleus dentatus {Nuc. dentatus Olivce). 

 It occupies the superior peduncle of the cerebellum. It has not yet been 

 recognized in the lower vertebrates, but it is probable that it exists, because 

 in these animals the superior peduncle enters the cerebellum. 



Of the connections and the definite course of the fibers of the cerebellum 

 there is, as yet, little known. 



To be sure, we possess minute descriptions for several different verte- 



