90 K. K. Oliver: 



Laterally (10a) the cerebral hemispheres are seen clearly to be 

 growing over the optic lobes, from the anterior posteriorly, and 

 from the dorsal surface ventrally. The approximation of the 

 cerebellum and the cerebral hemispheres has squeezed the optic 

 lobes in such a manner as to cause their greatest development 

 to take place ventrally, so that now the structures can be seen to 

 have become definitely ventro-lateral. The cerebellum has eleven 

 convolutions visible in this view, and the flocculi have assumed 

 the characteristic appearance found in the hatched bird. The 

 ventro-lateral depressions of the cerebral hemispheres have 

 become so faint as to be scarcely visible. The medulla is much 

 the same as in the previous stage. 



10c (Fig. 10, Section 1) shows a cut through the fore part of 

 the optic lobes, at the place at which the optocoele extends 

 furthest anteriorly. The chiasma is indicated ventrally, and the 

 most anterior convolutions of the cerebellum are shown. Dorsal 

 to the optic lobes in this section, the most posterior portions of 

 the cerebral hemispheres appear, so relegating the optic lobes to 

 a very definitely ventro-lateral position. 



In lOd (Fig. 10, Section 2) a section across the middle of the 

 optic lobes is given. The cerebellum is distinct in the centre 

 dorsally, and the optic lobes themselves are seen in a ventral 

 and lateral position. The optocoele is now to a great extent 

 obliterated by the great increase in size of the crura cerebri, 

 and assumes a roughly hemispherical shape in transverse section. 



In lOe (Fig. 10, Section 3), the enormous development of the 

 cerebellum is visible, taking up practically all the dorsal surface 

 in the section, and the optic lobes are most distinctly seen to be 

 lateral and ventral in position; the optocoele is not seen at all 

 in this section. 



The Adult Brain. (PI. XXXV.) 



The adult brain is inserted merely for comparison. I have 

 not worked it at all, so can give no description of it. 



