Order CETACEA— WHALES, DOLPHINS, AND 



PORPOISES 



Though externally the form of the various species of Whales and 

 Dolphins is fashioned in the likeness of a fish, when we come to examine 

 their internal structure and habits, we find this resemblance is only super- 

 ficial, and that they are really warm-blooded animals, wonderfiilly adapted 

 to an aquatic existence, bringing forth and suckling their young like 

 other mammals, and requiring to draw their breath from the atmosphere 

 by rising to the surface at frequent intervals. 



To facilitate this movement, the tail is made to act as a powerful 

 propeller, and is characterised by having the flukes or blades arranged 

 horizontally and not in an upright position, as in the tail of a fisli. 



The well-known spout of a whale is merely the exhausted air driven 

 from the lungs, and being warm and moist has the appearance of a 

 fountain of fine spray as it meets the outer and colder atmosphere, when 

 respiration takes place ; but should the animal blow just before reaching 

 the surface, water is driven upwards as well. About half an hour is said 

 to be the length of time a whale can remain under water, though they 

 usually come to the surface at much shorter intervals. The longest stay 

 of a Greenland Whale observed by Scoresby was fifty-six minutes. 



The fore limbs or flippers are outwardly formed like paddles, and 

 only capable of movement at the shoulder joint, but hidden within their 

 structure they have an arrangement of bones and muscles riot unlike those 

 of the human hand and arm ; while the hind legs, represented only by 



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