532 



H. F. Osboia 



ol fa Ctoria is composed of coarse tibres which arch forwards and 

 downwards. From this a minor division is given oflf directly to the 

 hemispheres which may be called the pars fron talis. The main divi- 

 sion passes forwards and scatters in the region of the olfactory lobes. 

 These unique relations confirm the view of Ganser vs Meynert that 

 the anterior commissure is a double bundle which places opposite 

 correspouding cell areas of the frontal, temporal and olfactory lobes 

 in commissural relation. 



? 



Sagittal section of tlie Ijraiu of Emj's eiirop aea '. 



The distribution of these fibres shows that the uppermost bundle 

 must represent the corpus c alio sum. While similar in position 

 and distribution this bundle differs from that in Emys (fig. 16) by 

 being less compact and containing fewer fibres. It consists of a 

 horse-shoe shaped tract traversing a mass of fine scattered nuclei. 

 Laterally the fibres pass above the ependyma-cells lining the ven- 

 tricle and are distributed to the layer of cells which extend in cres- 

 centic shape between the ventricle and the cortex. On either side 

 of this callosal bundle are numerous fibres for which do not pass 

 commissurally to the opposite hemisphere but descend in indepen- 

 dent tracts behind the anterior commissure. The further course of 

 these tracts cannot be followed in my sections but their relations to 

 the two commissures suggest very strongly those observed between 

 the fornix, corpus callosum and anterior commissure in the embryo 

 brains of the cheep (fig. 28), or kangaroo (fig. 24). Do these 

 tracts then represent the columns of the fornix? 



1 The folds at the sides of the 4ti' ventricle mf, have to my knowledge, 

 never been observed before in the adult reptilian brain. Goette observed them 

 inBombinator at the close of the tadpole stage. I have figured them in the 

 adult Ran a fig. 2, text). They are undoubtedly equivalent to the medullary 

 folds observed in the embryonic brain Kupffer,. 



