32 JoiKNAi. ()!• Comparative NEirROLocjv. 



as will be seen by reference to his paper elsewhere in this 

 fasciculus. 



IIHKE-TRACTS OF THE CEREKKUM. 



.Sections near the ventral surface of the cerebrum of the 

 lizard exhibit the numerous fibres radiating rather uniformly 

 cephalad and laterad from the cephalad extremity of the 

 ventral peduncular tracts. A strong portion passes directly 

 laterad, separating the gray matter of the occipito-basal lobe 

 completely from the remainder of the section. This tract 

 passes to the siu'face and is distributed by a number of 

 branches in the cortical region, dorso-cephalad of its ap- 

 parent destination. 



Dorsad to this corona radiata the whole base of the 

 cerebrum becomes filled with cells differentiating dorsad 

 into the niduli already described. A rather distinct tract 

 separates the intra-ventricular lobe from the frontal. This 

 can be traced backward to the corpus callosum, which con- 

 sists of few dark fibi'es passing from one intra-ventricular 

 lobe to the other by a sharp caudo-ventral curvature. 



As already stated, a very dense nidulus occupies the 

 terma caudo- ventral to the callosiun. The cells composing 

 it are small, and. as only the nuclei stain, present the ap- 

 pearance of Deiter's corpuscles. Beneath the anterior com- 

 missure in the lizard is a similar dense cluster, which forms 

 the only obvious demarkation between the prosencephalon 

 and diencephalon. The tracts in the frog are as in reptiles. 

 The taenia thalami can be traced with perfect ease from the 

 habena to the occipito-basal lobe, as also the fibres of the 

 anterior commissure. The origin of the descending fornix 

 fibres from the lateral extremities of the anterior commissure 

 is likewise as in reptiles. 



Prccco/i/ii/issura: — In the lizard it is rather difficult to 

 trace the relation of the olfactory tracts and the prjecommis- 

 sura, because of the vertical height of the brain and the in- 

 ferior olfactory development. Nevertheless, a distinct ven- 



