40 DOCTRINE OF EVOLUTION 



line of modification proceeding from a terrestrial animal 

 like a cat to semi-aquatic and marine types substan- 

 tially like an otter and a seal should, be carried further, 

 it will inevitably lead to forms possessing characters 

 such as those displayed by whales and the related por- 

 poises, dolphins, and narwhals of the order cetacea. In 

 their make-up all of these animals clearly possess the 

 general characteristics of mammals, and they constitute 

 collectively another limb which has sprung from the 

 same stock as the carnivora, although at an earlier 

 time. This we believe because of their plan of body 

 and because their peculiar organization fits them even 

 more perfectly than the seals for aquatic existence that 

 is then- only possible mode of life. In the case of the 

 whales the bony framework of the fore limb is again 

 like that of the cat's leg, although the whole structure is 

 a flexible finlike paddle. The hind limb has disap- 

 peared as an efficient organ, but the significant fact 

 is that small rudiments of hind limbs are present just 

 where corresponding structures are placed in the seal. 

 These vestiges cannot be reasonably accounted for, 

 unless they are the degenerate hinder limbs of a remote 

 four-footed ancestor. Furthermore the young whale 

 possesses a complete coat of hair, which is afterwards 

 replaced by blubber; but hair is a thatchlike coat to 

 shed rain, as the way the hairs lie on a terrestrial mam- 

 mal indicates. We are therefore forced to conclude 

 that whales have originated from four-footed animals 

 walking about on land, because no opposed explana- 

 tion gives so reasonable an interpretation of the 

 observed facts. 

 Another group of familiar animals materially rein- 



