THE LOWER PRIMATES 



in this animal. The Sylvian fissure is a prominent sulcus whose angulation 

 with the base hne of the brain is slightly less than 50°, showing in this regard 

 a general tendency to approach the condition of the higher primates. The 



FIG. 73. DORSAL SURFACE OF BRAIN, CALLITHRIX JACCHUS (MARMOSET). 



[Actual Length, 29 mm.] 

 Key to Diagram, obl., Oblongata; sup. long, fiss., Suporior Longitudinal Fissure. 



Sylvian fissure, however, is relatively short and extends I3acl:^\•ard and 

 upward for something less than half the distance of the entire lateral surface. 

 Below and behind the Sylvian fissure is a slight indenture indicating the 

 position of the superior temporal fissure, corresponding in its general position 

 to the sulcus parallelus in the lemur's brain. A slight indenture above and in 

 front of the Sylvian fissure indicates the position of the sulcus centralis which 

 forms the faint boundary by means of which the limits between the frontal 

 and parietal lobes may be established. There is no evidence of any parietal 

 sulci or of any incisure which may be considered as the homologue of the 

 sulcus simiarum. 



LOBATION 



The lobation in the marmoset brain, therefore, is only most rudimen- 

 tarily outlined. Distinction may be made between the parietal, parieto- 



