200 



THE BRAIN OF QUADRUMANA. 



bral lobes, and possesses a large posterior cornu with 

 a wcU-dovelopcd hippocampus minor." 



In the smallest Lemurs, the Hemispheres are quite 

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



* Sylvian' (fig. 103, 5). 

 Even the larger Lemurs 

 possess only a few pri- 

 mary fissures. 



In the diminutive hut 

 active Marmoset (fig. 

 101), the Cerebral Hemi- 

 spheres are relatively 

 argcr, 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- 

 Only one fissure 

 is seen — the 'Sylvian' — 

 forming the boundary lino Ix^twoen pjirts which will subse- 

 quenlly 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 

 * ])arM,nel fissure ' (fig. 105, 9). This runs along the centre 

 of tlio TcMuporal Lobe, and backwards towards the upper 

 and inner edge of the Hemisphere. Both these fissures 

 are less vertical and slope backwjirds more than the corre- 



* Tlic names of these lobes of ilio Brain nre derived from those 

 of the bones of the skull ac^ainst which they lie. 'I'he two lobes 

 above named together constilnto what was formerly prineipally 

 ripokeii of as the ' Midillo Loue.' 



Fin. 100. — Hv.iin (it tiio iidwlor Monkey (/I/// 

 cetcs), Hccn from iibovo. (Duiicjui.) Ij, Lungitu- tlOUS 

 diual Fis.suro ; F, Fissuro of Sylvius. 



