4i8 



THE INTERMEDIATE PRIMATES 



of the substantia gelatinosa trigemini. This trigeminal protuberance 

 at the more ccphahc levels of the oblongata is concealed from view by the 

 superposition of the fibers entering the restiform body. In the most cephalic 



FIG. 197. VENTRAL SURFACE OF BRAIN STEM, HYLOBATES HOOLOCK. 



[Actual Length 45 mm.] 



Key to Diagram, cer. ped. and cerbl. peduncle, Cerebral Peduncle; opt. ch.. Optic Chiasm; ventro 

 MED. SULCUS, Ventromedian Sulcus; 3RD N., Third Nerve; 8th nr.. Eighth Nerve. 



portion of the lateral surface appears a well-defined protuberance, the 

 tuberculum acusticum. 



The dorsal surface of the oblongata presents its characteristic divisions, 

 the ventricular and infraventricular portions. The infraventricular portion is 

 characterized by the tj^pical dorsomedian septum, upon either side of which 

 appears a well-defined clava, separated by a dorsal paramedian sulcus from 

 an equally well-defined cuneus. These elevations on the dorsal surface indi- 

 cate respectively the presence of the nucleus of Goll and the nucleus of 

 Burdach. 



