520 THE HIGHER ANTHROPOIDS 



many details of their primordial subjugation in that tonimunity ol interests 

 necessary to cooperation of the entire musculature tor the purposes ol locomo- 

 tion. In their more recently acc[uned cajxicity, the extremities de\eli)|)ed 

 numerous performances, ne\v both m design and range, which called lor 

 expansions in the controlling mechanisms of the central ner\()us system. 

 The neopallium was the brain's structural response to this demand, simul- 

 taneously with w hich the cerebellum expanded to atlord a needed increase ot 

 coordinative control lor these nc\\ activities. It is evident that all ol this 

 motor adaptation belonged to what may be called ncohintiic or'^ani/.alKin, 

 which diHers materially Irom those older, more primordial activities which 

 arc attributed to the jHilcokinclic oriiuni/.ation of lower vertebrates. The j^on- 

 tile structures denoting this neokmetic expansion in the pallio-ponto-cere- 

 bellar system are e\ident in the orang; il. not so ])romiiient as m the higher 

 anthropoids, they are still much more conspicuous than m the lower and 

 intermediate primates. 



The distinction between the basis pontis and tegmentum pontis is 

 established b\- the transverse ])osition of the nu'sial lillet (Mf) which 

 occupies the most \entral position m the tegmental portion ol the stem 

 at this level. The transN'erse fibers ol the basis pontis arc shown m their 

 collected mass as they constitute the middle cerebellar peduncle (Mcp). 

 The central gray matter h)rnis the lloor of the fourth \iiitricle (i\) and 

 is specialized in its median portion as a nucleus giving rise to the sixth 

 cranial ner\e ( N ab). The libers of this ner\e ( N6) pass from the nucleus in 

 the direction ol the basis toward their point of emergence in the bulbopontile 

 sulcus. Latt'ral to this nucleus is a denst' bundle of emergent libers constitut- 

 ing the tourth jxirt of the intramedullary course of the facial ner\e (N~). 

 Mesial to the bundles forming this emergent root is the caudal extremity 

 of the nucleus facialis itself. The roof of tlu' xcntrich' is formed In the 



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