VotumMeE XIII. 1903. NUMBER I 
THE 
JournaL or Comparative Neurovocy. 
4 
THE FORE-BRAIN OF MACACUS. 
By Wm. Wo tre Lesem, M. A. 
With Plates I and II. 
The present article is the result of investigations upon the 
simian brain pursued by the writer during the winter of Ig00 
in the anatomical laboratory of Columbia University. A 
careful search of the bibliography of the simian brain failed to 
show any article dealing with the species in question. Here 
and there the writer came across rather poor drawings of the 
macaque brain but nowhere did he meet with any description 
thereof except in Flatau and Jacobsohn’s Comparative Anat- 
omy of the Central Nervous System of Mammals. In the 
Anatomical Museum of Columbia University the writer has 
had access to a sufficiently large number of macaque brains to 
render his observations fairly accurate. 
Compared with the dog, Macacus presents many striking 
advances. A higher type of gyri and sulci, a well developed 
occipital lobe with a posterior cornu, a calcar avis, a prominent 
forceps major, and an enormously developed temporo-sphenoti- 
dal lobe are some of the points which will be discussed in the 
ensuing pages. 
Whereas in the dog the ventral aspect of the encephalic 
segments lies almost entirely in the same plane, the brain of 
Macacus presents that convexity of the pons Varolii so marked 
in man. The pons of Macacus differs moreover from that of 
the carnivores in being actually larger than the medulla. In 
the carnivores the crura cerebri are plainly visible upon the base 
of the brain as two large bundles of fibres which extend from 
the pons and diverge to enter the cerebral hemispheres opposite 
