654 



THE HIGHER ANTHROPOIDS 



tant features. Ujjon the \-eiitral aspect of the oblongata are t\\o pronounced 

 elevations, one on either side of the ventroinesial lissure, the long pyra- 

 mids, in turn separated from two more laterally placed eminences, the 



I K;. 2l)y. \ENTRAL SURFACE OF BRAIN STEM, GORILLA. 

 [Actual Length 42 nini.) 



Key to Diagram, thai-, ihjd^ , Trapezoid Body. 



inferior olivar\- bodies, by w (.•11-delined i^reolixary sulci. At the caudal 

 extremity of the pyramid, large bundles of interlacing fibers interrupt the 

 ventromesial lissure as the p\ ramidal decussation carries the fibers of this 

 system from one side to the other across the median line. The interlacing of 

 these crossing pyramidal libers is more conspicuous than in the lower and 

 intermediate primates. Upon the lateral surface of the oblongata is the tuber- 

 culum trigemini which is se|)aratcd from the interior olivary body by the 

 deep post-olivar\ sulcus. The latter, as it extends cei^halad, becomes 

 obscured by the dorsal shifting of the dorsal spinocerebellar tract entt'ring 



