238 THE LOWER PRIMATES 



material beginning to infiltrate intu the bundles of the pyramidal and the 

 pallio-pontile system of fibers, producing a lacework of nerve cells and fibers 

 between the mesial aspects of the two lateral and mesial buttresses. As is 

 the case in the lemur and marmoset, the deep layer of the pontile nuclei, 

 together with the dorsal portions of the lateral and mesial buttresses, becomes 

 continuous with and serves, so to speak, as a support for the mesencephalic 

 substantia nigra. 



The Vestibular Complex 



The reconstruction of this nucleus has been described as a condensation 

 in the reticular formation arising at about the middle of the ventricular por- 

 tion of the medulla oblongata. It appears first as a small, wedge-shaped mass 

 of gray matter between the subependymal gray matter of the ventricular 

 iloor and the dorsal mass of the nucleus of Burdach. The nucleus of Deiters 

 expands rapidly, becoming roughly triangular in shape, with its base 

 upon the subependymal gray matter, its lateral boundary facing toward the 

 nucleus of Burdach, and its mesial boundary toward the subependymal 

 ventricular gray matter and the reticular formation. The triangular nucleus of 

 Schwalbe continues somewhat cephalad to the lateral ventricular recess 

 and then merges w ith the reticular formation. The nucleus of von Bechterew 

 is situated in the lateral wall of the fourth ventricle cephalad to the 

 lateral recess. This last nucleus is so feebly developed as to be scarcely 

 demonstrable in the model. 



The Cochlear Complex 



As reconstructed, this nuclear collection conforms with the type found 

 in the lemur and the marmoset. It represents a trough which covers the 

 caudal, lateral and cephalic aspects of the entering cochlear nerve root. The 



