237 



ORDER VI. CETACEA. 



207. This order, in regard to the number of species included 

 in it, ranks nearly the lowest "among the orders of Mammalia ; 

 but in regard to the bulk of the individuals which it contains, it 

 far surpasses every other tribe of animals at present existing, 

 being only rivalled by some of the gigantic Lizards of former 

 epochs. No terrestrial quadruped, not even the Elephant and 

 Hippopotamus, can be compared to the Whale ; and even the 

 smallest species, the Dolphins and Porpoises, much surpass the 

 average size of land animals. As already mentioned ( 24), 

 the form of the animals of the Whale tribe bears so strong a 

 resemblance to that of Fishes, that most of the ancient Zoologists, 

 and even some modern ones, placed them in the same class ; and 

 they are still spoken of as " fish" in common parlance, notwith- 

 standing that a knowledge of their internal structure has shown 

 that they are, in every essential respect, Mammals. 



208. The modifications in the form of the body, which have 

 been pointed out as adapting the Seals for aquatic progression, 

 are here carried still further. The body is still more lengthened, 



FIG. 120. TAIL-FIN OF WHALE. 



the tapering of its hinder portion still more gradual, and the 

 anterior extremities still more exclusively adapted for propulsion 



