MAN. 337 



convolutions bounding which constitute the opercular lobe* The 

 frontal lobe is anterior to this, the parietal lobe posterior to it, and 

 there is an occipital lobe at the extreme back of the hemisphere. 

 Besides this, there is a small central lobe (island of Eeil) which 

 can only be seen by separating the lips of the Sylvian fissure. 

 The opercular lobe has been mapped out into lower, middle, and 

 upper motor areas for the muscles of the face, leg, and arm 

 respectively. The following sensory centres have also been 



Fig. 108. MAN. Embryo in Uterus, showing Foetal Membranes (from 

 Macaiister, after Longet). al, Stalk of allaiitois ; am, amnion ; c, neck 

 of uterus ; ch, chorion ; dr, decidua reflexa ; ds, decidua serotina ; du, 

 decidua vera ; nb, yolk-sac ; z, placental villi ; z 1 , transient villi. 



recognized (with less certainty) in other lobes, (a) Sight, occipital 

 lobe ; (b) Hearing, uppermost convolution of temporal lobe (T) ; 

 (c) Smell, inner side of temporal lobe, just below Sylvian fissure. 

 The corpus callosum is relatively very large, and it is much more 

 strongly curved than in the rabbit. The anterior commissure is 

 smaller, and so are the olfactory lobes. There are two corpora 

 mammillaria (c. albicantia). 



The cerebellum is well-developed, but, in comparison with the 



* Many anatomists do not recognize the opercular lobe as a distinct sub- 

 division, and take the Rolandian fissure as the line of demarcation between 

 frontal and parietal lobes. 



2 22 



