NERVOUS SYSTEM. VERTEBRATA. 301 



Suborder PROBOSCIDEA. 

 Family ELEPHANTID^:. 



D. 391. The brain of an Asiatic Elephant (Elephas indicus) : 

 a female about 25 years old. 



[The arrangement of the sulci in this brain is funda- 

 mentally different to that represented by Krueg (Mayer) 

 and Flatau and Jacobsohn.] 



An Elephant weighing approximately 46 times as much 

 as a Man is provided with a brain almost four times the 

 size of the human brain. In comparison with the brain- 

 weights of other large Ungulates it must be regarded as a 

 large and well-developed brain. According to the most 

 recent studies on the question of the size of the brain, the 

 dimensions of the cerebral hemispheres, which are chiefly 

 responsible for the great variations in the size of the mam- 

 malian brain, are in any given Order determined largely, 

 or even wholly, by the extent of the sensory surfaces. 

 Thus an animal like the Elephant possessing an enormous 

 surface-area would have a correspondingly large extent of 

 cerebral cortex, But the degree of this cortical repre- 

 sentation of sensory surfaces, or " cephalisation," as it is 

 called, varies in different orders, so that, for instance, a 

 given area of bodily surface in a Primate is represented by 

 a much larger cortical area than the same extent of surface 

 would be in an Ungulate. This degree of " cephalisation" 

 has also rapidly increased, even in the same Order, within 

 recent (geologically speaking) times. Thus the Titano- 

 therium, a Miocene Perissodactyle as large as the Elephant, 

 was provided with a brain considerably smaller than that 

 of the Horse. On the other hand, this brain was very con- 

 siderably greater than that of the Eocene Dinoceras. It is 

 not improbable that the enormous extent of the neopallium 

 in the Elephant proportionately much greater than in 

 other Ungulates becomes necessary to such an immense 

 animal which lives in the open, because such a creature is 

 naturally exposed to greater risks of pursuit &c. than a 

 smaller animal, and needs to display greater cunning to 



