RECONSTRUCTION OF PITHECUS RHESUS 



397 



increasing ni size, into the tegmentum of the pons, where it is massive in 

 form and suppHes the main bulk of the gray matter of the meteneephalic 

 tegmentum. 



FIG. 1 86. LATERAL SURFACE OF GRAY MATTER OF BRAIN STEM, 

 PITHECUS RHESUS. 



Key to Diagram, dors, cochl., Dorsal Cochlear Nucleus; inf. coll.. Inferior Colliculus; inf. olive, 

 Inferior Olive; lat. gen. body. Lateral Geniculate Body; nuc. of burdach. Nucleus of Burdach; nucl. of 

 DEiTERs, Nucleus of Deiters; nucl. of goll. Nucleus of GoII; pontine. Pontile Nucleus; subst. gel. 

 ROLANDO, Substantia Gelatinosa of Rolando; subst. nigra, Substantia Nigra; vent, cochl.. Ventral 

 Cochlear Nucleus; vent, gray col., Ventral Gray Column. 



Above the level of the olivary complex the ventral surface of the reticular 

 formation recedes rather rapidly from the surface, providing along its ventral 

 surface a deeply excavated bay for the lodgment of the trapezoid body, 

 formed by the secondary fibers from the cochlear system. Continuing upward 

 in the metencephalon the reticular formation gradually diminishes in bulk, 

 separated at first from the deep layer of the pontile nuclei by the trapezoid 

 body. Above the level of the trapezoid body, the reticular formation comes 

 into fairly close contact with the deep layer of the pontile nuclei and presents 



