APPENDIX 



present in the cetacean flipper, but they become greatly 

 flattened and overlaid with adipose tissue to form a paddle. 

 In the right whales the five fingers of the mammalian hand 

 are present, but in others one finger has been lost, and the 

 digits are greatly elongated. The scapula, or shoulder blade, 

 is a wide, flat, fan-shaped bone, and the clavicles, or collar- 

 bones, have entirely disappeared. The hind-limbs are rudi- 

 mentary, when present at all, only being represented by 

 bony nodules, and the pelvis is reduced to two spindle-shaped 

 bones quite unlike that of land mammals. 



The skeleton of each group of the Cetacea, although 

 similar in general characters, varies enormously in the de- 

 tails of construction, and to anyone interested in osteology 

 will prove a fascinating subject for investigation. 



IV. ADAPTATION AS SHOWN BY THE CETACEA 



There are many indisputable evidences that whales once 

 lived upon the land and walked upon four legs like ordinary 

 quadrupeds, yet how remarkably different from any land 

 mammal is their present form ! 



We see that almost all aquatic creatures have torpedo- 

 shaped bodies, which offer the minimum of resistance to 

 their passage through the water. Thus as the whales gradu- 

 ally changed from a terrestrial to an aquatic life their bodies 

 assumed the elongated form essential for successful exist> 

 ence in a liquid medium. 



Accompanying this change of bodily shape was the elimi- 

 nation of all unnecessary structures which offered resistance, 

 and the whale's smooth, soft, hairless skin was one of the 

 results. But the hair of a land mammal acts as a non-con- 

 ductor, preventing the heat of the blood from being absorbed 

 by the air, and as the whale's body became naked it was 

 necessary to blanket it with some other protective covering; 

 thus the layer of fat or blubber developed between the skin 

 and the flesh. Fish and amphibians do not need a warm 



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