THE LION AND HIS KIN 8i 



had assumed a growth relatively exaggerated as in 

 Dinoceros, and yet the flange never attained to more than 

 feeble development. We cannot rest content with the 

 theory that the flange is due to the constant stimulus of 

 blows struck against this region of the jaw during the 

 lateral movements which take place when feeding. Were 

 these animals alive to-day it could be tested by extracting 

 the tusks during infancy, when, the stimulus being removed, 

 the flanges should not appear. 



There are yet other aspects of the skull of Dinoceros 

 which may well be considered here. The first concerns 

 the excessive armature of horns, there being no less than 

 three pairs supported on massive bony cores ; and the 

 second the ridiculously small brain cavity which is pro- 

 portionately smaller than that of any other known 

 mammal, recent or fossil. This poverty of brain-power 

 was probably one, if not the chief, factor among the causes 

 which brought about the extinction of this strange beast. 

 Even more formidable horns were borne by the extinct 

 Arsinoetherium. But this animal did not display the 

 double armature of horns and tusks. 



Among the Carnivora monogamy is the rule, though 

 the Lion is occasionally polygamous. But the Eared- 

 seals {Otaria)^ or Sea-lions, and Sea-bears afford a striking 

 example of polygamous species and of the ferocity they 

 display when sexually excited. These animals, moreover, 

 are capable of the most astonishing powers of endurance 

 and vitality, exceeding indeed that of all other mammals. 

 Since the habits of the Northern Fur-seal (Otaria ursina) 

 have been more carefully studied than those of any others, 

 it may serve as a sample of the rest. 



Living for the greater part of the year in the open 

 sea, the old bulls — animals of six or seven years old — 



6 



