266 PROCEEDINGS OP THE ACADEMY OF [1884. 



The Cerebellum (figs. 6, t). — Numerous as are the errors 

 which at present prevail in the literature of the amphibian brain, 

 none are more striking than those relating to the cerebellum.^ 

 It is said to retain its embryonic condition of a small band-like 

 structure stretching over the fourth ventricle. Now it happens 

 that the amphibian cerebellum is a flat structure, and if viewed 

 on edge, as is the case in looking down upon the frog's brain, it 

 does appear very small ; if, on the other hand, it is seen in ver- 

 tical longitudinal section, its large bulk, relatively to other parts, 

 is at once apparent. If, further, as will be done in another 

 paper, a corresponding section of an amphiuma brain be super- 

 posed upon the frog section, we find that the former barely covers 

 one-twenty-fourth of the diameter of the latter, although the 

 Amphiuma is a very much larger animal. The description 

 referred to above, then, is as exaggerated when applied to the 

 frog as it is true of such forms as Amphiuma, Menopoma and 

 Menohranchus. 



In Amphiuma, the cerebellum is reduced to its simplest pos- 

 sible expression. It seems doubtful whether it contains any 

 nerve cells whatever. In Menopoma, however, a few cells similar 

 to those in the optic lobes, can be observed on either side of the 

 transverse fibres which make up the larger part of this body ; it 

 is difficult to distinguish these cells from those of the ependyma. 

 Notwithstanding the character of this bod}', its main relations to 

 the adjoining parts are precisely similar to those of the higher 

 vei'tebrates. These relations have already been indefinitely 

 indicated \>y Stieda. (1.) From the lateral tips of the medulla 

 arises a column of fibres on either side, which arches forward ; 

 here the columns are reinforced by fibres apparently arising from 

 lateral cell-masses, these columns turn back and enter the cere- 

 bellum. (2.) Passing beneath these columns is another pair, 

 which diverge and then converge as the}' enter the pars peduncu- 

 laris of the mesencephalon ; they can be followed some distance 

 forwards upon either side of the mesocoelia. (^3.) Passing 

 directly forward from the ventral surface of the cerebellum, a 

 few scattering fibres enter the valvula and with some doubt can 

 be followed into the cells of the roof of the optic lobe. In one 

 and two we recognize the post- and pme-pedunculi or inferior 



^ Mihalkovics, loc. cit., p. 56 ; also, Wiedersheim, Lehrbuch der Ver- 

 gleicheuden Anatomic, 1883, p. 397. 



