on the whole body the embryos are much better supplied. 

 The embryos also show signs of dermal plates which make it 

 possible that these animals may once have been as completely 

 armored as the armadillo is to-day. With the loss of both 

 hair and dermal plates the blubber has been developed 

 to keep th-e animal warm. 



One of the many adaptations to aquatic life is the shorten- 

 ing of the fore limbs and their conversion into paddles, which 

 assist in balancing the body, but are of little use in sv/im- 

 ming. The hind limbs must have been entirely useless for 

 they have completely disappeared except for the small bones 

 of the pelvis deeply buried in the flesh. One old theory sup- 

 posed that the great flukes of the tail, upon which the whale 

 depends almost entirely in swimming, were the hind limbs 

 migrated backwards. There was nothing inherently im- 

 probable in this supposition but it was conclusively over- 

 turned by the discovery that the flukes develop as lateral 

 flanges on the tail of the embryo at a time when distinct ru- 

 diments of the hind limbs are present. 



The horizontal position of the whale's flukes is strikingly at 

 variance with the universal vertical tail fin of the fishes. The 

 vertical fin is adapted for turning the body to one side or the 

 other, while the horizantal flukes are more effective in ver- 

 tical motions, and so are specially suited to the needs of the 

 whale which must needs spend much of its time in coming 

 up to the surface for air, something which the fish never has 

 to do. The whales breathe through nostrils or blow- 

 holes situated at the highest part of the head— far back in 

 the case of the baleen whales, but at the very tip of the great 

 square head of the sperm whale. On coming to the surface 

 to breathe the whale first expels the vitiated air from its 

 lungs, and this, .being warm and moist, condenses in the 

 colder air to form steam or spray. This is the "blowing" of 

 the whale, and if it is begun just before the surface is reached 

 a little salt water may be carried up also, but water from the 

 mouth is never expelled through the nostrils, for no such 



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