420 PHYSIOLOGICAL SERIES. 



occipital sulcus, are found in the triangle partially formed 

 by the Simian sulcus and the inferior occipital sulcus. 



There is a very rudimentary superior postcentral sulcus. 

 In addition to the typical sulcus rectus and sulcus arcuatus 

 there is a small " inferior transverse " sulcus of Eberstaller 

 (between the lower ends of the latter and the central 

 sulcus) and a small " diagonal " sulcus (in front of the 

 lower end of the arcuate sulcus) *. 



An irregular series of small furrows represents the 

 superior precentral and superior frontal sulci. Simple 

 orbital and fronto-orbital sulci are present. 



The floccular lobes of the cerebellum are still very large 

 and retain those features common to most mammals. The 

 flocculus consists of a narrow band of small folia encircling 

 the eighth nerve. The paraflocculus consists of a much 

 larger and broader band surrounding the flocculus. Its 

 mesial lobule lies in front of (and without minute exam- 

 ination is indistinguishable from) the flocculus. From the 

 antero-lateral part of the paraflocculus projects a small, 

 though widely salient, " petrosal lobule." But in contrast 

 to the condition found in the Cebida3 and many Cerco- 

 pithecidse, the " petrosal lobule " constitutes a very small 

 part of the paraflocculus. 



As this is a larger brain than that of any Ape yet 

 considered, it affords an excellent demonstration of the 

 great increase in size and prominence of the olivary bodies 

 and pyramidal tracts. Although the pons has become very 

 broad, the large trapezoid bodies are still uncovered, as in 

 lowlier mammals. 0. C. 1338 A a. 



D. 626. The brain of a Yellow Baboon (Papio babuin), 

 The left hemisphere is separate. 



In the presence of a deep long collateral sulcus (sucli as 

 we shall see in specimen D. 627) the occipi to-temporal 

 almost completely disappears as a separate sulcus, and lli- 

 inferior occipital sulcus becomes smaller. 



In the right hemisphere both the lateral and mesial 

 olfactory tracts are unusually clearly shown. 0. C. 1338 A/. 



* This sulcus, called " diagonalis " by Eberstaller, is not the furrow rail. -I 

 by this name in other Mammals by Krueg. The latter, in all probability, 

 becomes the fronto-orbital in Primates. 



