THE BRAIN AND THE BODY 



199 



Mammal possibly had the physical advance ])laced 

 within its reach. The earliest eiitherian Mannnal 



Fig. 72. — Diagram taken from the Drawing by Professor 



G. Elliot Smith of the Brain of Oniithorhj/nchus. 

 The brain is in medial section and the commissures are cut across. 



There is no corpus callosum. 



Fig. 73. — Diagram of the Human Brain in Medial Section. 



The commissures are marked in a similar manner to those sliown 

 in Fig. 72. Note the size of the corpus callosum. 



possessed the cerebral condition which made it ]inssihle 

 for it to take full advantage of the physical advance. 



