656 THE HIGHER ANTHROPOIDS 



the somatic musculature; the cquall\- prominent inferior oli\c", justifying the 

 inference that coordination of simuhaneous movements in eyes, head and 

 hands has undergone further extension; and the more clearly marked defini- 

 tion of the dorsal sensory Held. This augmentation involves both the column 

 of GoII and the column of Burdach. It more particularly affects the size of the 

 latter, thus denoting accessions to the inllux of sensory impulses from the 

 upper extremity and hand. The inferior angle of the ventricular portion of 

 the oblongata is bounded by the diverging clava and cuneus. In this case the 

 cuncus extends a greater distance ccphalad than the cia\a. At the lateral 

 recess the cuneus attains the level of the door of the ventricle, at which point 

 fibers from the tubercuhnn acusticum enter the ventricle as the strands of 

 the striae acusticae, while the middle peduncle of the cerebellum forms the 

 sharp cephalic boundary of this recess. The iloor of the ventricle near the 

 inferior angle presents the narrow trigonum hypoglossi and, lateral to this, 

 the fovea vagi. There are also indications of an area plumiformis and an area 

 postrema, although neither is so marked as in the average human oblon- 

 gata. A deep median sulcus divides the floor of the ventricle longitudinally 

 into two symmetrical halves. 



In the region of the lateral recess a well-defined prominence makes its 

 appearance. Its relief is not so conspicuous as in the intermediate or e\ en in 

 the lower primates. It marks the ])osition of the vestibular complex. The 

 superior triangle of the fourth \entricle is bounded by the middle cerebellar 

 peduncles and the libers constituting the superior cerebellar peduncles. Its 

 lateral walls comerge toward the caudal orilice of the Sylvian ac]ueduct 

 and pass beneath the inferior colliculi and the superior medullary velum in 

 the isthmial portion of the stem. 



The Pons Varolii. The ventral surface of the oblongata comes to an 

 abrupt termination at the bulbopontilc sulcus abo\c which the pons X'arolii 

 rises in strong relief as a massive structure crossing the stem. The pons of the 



