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ORDER 11. CETACEA 1 . 



The order Cetacea comprehends all those animals so familiarly 

 known under the trivial names of "Whale, Black-fish, Grampus, Dol- 

 phin, and Porpoise, and which from their fish-like form and aquatic 

 mode of life are, even at the present day, considered by a majority of 

 persons as true fish. 



Their genuine position among the first-class of vertebrated animals is 

 clearly established by the one incontrovertible fact, that the female, 

 bearing mammsa, suckles her young. 



Beyond this important condition, there are, however, so many other 

 interesting points of departure between the whale and fish tribes, so 

 thoughtlessly associated together, that I cannot refrain from offering a 

 few pertinent comparisons for the consideration of the student. 



The young of the Cetacese are born alive, and such also is the case 

 with those of many kinds of fish ; but the young of the whale tribe, 

 during the entire period of their fetal condition, draw their nourish- 

 ment direct from the parent by the agency of the connecting placenta, 

 and after birth are wholly dependent upon the milk drained from her 

 breasts ; not so with the offspring of ovo-viviparous fish, the blennies, 

 silures, sharks, &c., whose embryo is attached by a pedicle to a yolk, 

 and both enclosed within an egg, externally protected by a membran- 

 ous envelope. This egg enlarges within the body of the female, until, 

 by the gradual and entire absorption of the alimental yolk, the foetus 

 is fully developed, and the young having thus been completely hatched, 

 breaks the egg and the membrane which retained it, and passively 

 peeks an independent living, conforming precisely in all the elements of 

 foetal vitality and after-growth to the young of the eggs scattered in 

 the water by oviparous fish. 



Again, the blood of all Cetaceans is warm, and consequently they 

 are compelled to breathe the atmospheric air by means of true lungs, 

 placed within the cavity of the chest, and have to rise periodically to 

 the surface of the water in order to respire ; should any accident frus- 

 trate this indispensable requirement, they would literally be drowned. 



They are also provided with necks, which contain the typical number 

 (seven) of vertebrae, common, with three exceptions only 2 , to the whole 

 mammalian group, although these necks are extremely short and thick ; 

 their eyes are protected by lids, and many species even possess the 

 organ for secreting tears : their ears exhibit external openings ; their 

 nostrils are placed on the crown of the head ; their caudal fin invari- 

 ably assumes' the horizontal position ; and their body is covered with a 

 smooth, almost hairless, leathery hide. 



1 KTJTOS, a whale. 



2 The common Sloth (Bradvpua tridactylua) : the Manatee (Manatus Australis), 

 and the Steller's Manatee (Ebytina SteUeri.) 



