250 



THE MAMMALIA. 



bear witness, however, to 

 their having possessed an- 

 cestors with four legs. 1 

 The front limbs remain 

 wholly within the known 

 structure of the mammal 

 leg, as may be seen by 

 that of the dolphin on Fig. 

 46. The toothed whales 

 are almost without excep- 

 tion five-fingered, even 

 though in most cases the 

 thumb and the little finger 

 appear very much reduced. 

 This, moreover, shows them 

 to be geologically older than 

 the Whalebone whales ; for 

 of these only the smooth 

 whales (Balcena) possess five 

 fingers ; in the others the 

 thumb has completely dis- 



1 The modifications which the 

 whales have experienced as mam- 

 mals in water, have been admir- 

 F IG . 46. Eight Fore-limb of ably described by Prof. Flower, 

 Delphinus delphis. After ' Whales in the Past and Present,' 

 van Beneden and Gervais. Kostnos, vii. 1883. 



n 



