290 



THE BRAIN OF QUADRCMANA. 



bral lobes, and possesses a large posterior cornu with 



a well- developed hippocampus minor." 



In the smallest Lemurs, the Hemispheres are quite 



smooth, or, at most, show traces of one primary fissure the 



1 Sylvian ' (fig. 103, 5). 

 Even the larger Lemurs 

 possess only a few pri- 

 mary fissures. 



In the diminutive but 

 active Marmoset (fig. 

 104), the Cerebral Hemi- 

 spheres are relatively 

 larger, so that they com- 

 pletely cover and even 

 slightly overlap the pos- 

 terior border of the Cere- 

 bellum. They are, how- 

 ever, quite smooth and 

 wholly devoid of convolu- 



J 



Only One fisSUl'C 

 ig geen _ the < ^{^ '_ 



forming the boundary line between parts which will subse- 

 quently be spoken of as the Parietal and the Temporal 

 Lobes.* In the Squirrel Monkey, another small allied 

 form also notable for its extremely active habits, a fissure 

 below and behind the Sylvian is added known as the 

 ' parallel fissure ' (fig. 105, 9). This runs along the centre 

 of the Temporal Lobe, and backwards towards the upper 

 and inner edge of the Hemisphere. Both these fissures 

 are less vertical and slope backwards more than the eorre- 



* The names of these lobes of the Brain are derived from those 

 of the bones of the skull against which they lie. The two lobes 

 above named together constitute what was formerly principally 

 spoken of as the ' Middle Lobe.' 



FIG. 109. Brain of the Howler Monkey (My- 

 cetes), seen from above. (Duncan.) L, Longitu- tlOnS. 

 dinal Fissure ; F, Fissure of Sylvius. 



