394 PHYSIOLOGICAL SERIES. 



branch which is directed forwards. The an tero- superior 

 extremity of a definite inferior occipital sulcus approaches 

 very close to the lower end of the Simian sulcus. This 

 leaves a comparatively large occipital area free from any- 

 tiling more than faint depressions, and in the possession of 

 this character, these brains of Pitlieda and those QfBruchy- 

 urus form a strong contrast to that of Lagothrix. 



Anteriorly to the Sylvian and intraparietal fissures there 

 is a well-developed central sulcus and immediately in 

 front of this another sulcus, shorter than, but having the 

 same general direction as, the central sulcus itself. The 

 sulcus rectus is tri-radiate (on the left hemisphere). On 

 the orbital surface is an H-shaped orbital sulcus. 



The calloso-marginal sulcus (prolonged forwards into a 

 genual), the internal parieto-occipital, the T-shaped calcarine 

 (with a single long collateral sulcus running superficially 

 into it), and the hippocainpal fissures occupy their usual 

 positions (for which see, inter alia, especially accounts of 

 Alonatta and Lagothria;). 0. C. 1337 Fa. 



D. 567. The brain of a White-nosed Saki (Pithecia albinasia). 

 The right hemisphere has been detached. 



Its general appearance is remarkably similar to D. 566, 

 but the Sylvian fissure does not quite reach the parallel 

 sulcus even superficially. In the left hemisphere of this 

 specimen, D. 567, as in the left hemisphere of D. 566, 

 the connection between the two sulci is closer than that 

 obtaining in the corresponding right hemispheres. Near 

 the temporal pole there is a short, well-marked inferior 

 temporal sulcus. 



The sulcus seen in front of the central fissure in D. 566, 

 and named pre-central, is here represented by two short 

 sulci, an upper and a lower on the left side. Further forward 

 there is a short oblique sulcus above the sulcus rectus. 



Note the peculiar shape and direction of the orbital sulci. 



O.C. 1337 F^. 



D. 568. The brain of a Red Uakari (Brachyurus rubicundus), ( ? ). 

 The left hemisphere h;i> Ix-en detached. 0. C. 1337 F r. 



