230 WHALES, PAST AND PRESENT xv 



the animal must have been in a too helpless condition to 

 maintain its existence during the transference, if it took 

 place, as we must believe, gradually. It is far more reason- 

 able to suppose that whales were derived from animals with 

 large tails, which were used in swimming, eventually with 

 such effect that the hind-limbs became no longer necessary, 

 and so gradually disappeared. The powerful tail, with lateral 

 cutaneous flanges, of an American species of otter (Pteronura 

 sandbacJiii\ or the still more familiar tail of the beaver, may 

 give some idea of this member in the primitive Cetacea. I 

 think that this consideration disposes of the principal argu- 

 ment in favour of the whales being related to the seals, as 

 most of the other resemblances, such as those in the characters 

 of their teeth, are evidently resemblances of analogy related 

 to similarity of habit. 



As pointed out long ago by Hunter, there are numerous 

 points in the visceral organs of the Cetacea which far more 

 resemble those of the Ungulata than of the Carnivora. These 

 are the complex stomach, the simple liver, the respiratory 

 organs, and especially the reproductive organs and structures 

 relating to the development of the young. Even the skull of 

 Zeuglodon, which has been cited as presenting a great re- 

 semblance to that of a seal, has quite as much likeness to one 

 of the primitive pig -like Ungulates, except in the purely 

 adaptive character of the form of the teeth. 



Though there is, perhaps, generally more error than truth 

 in popular ideas on natural history, I cannot help thinking 

 that some insight has been shown in the common names 

 attached to one of the most familiar of Cetaceans by those 

 whose opportunities of knowing its nature have been greatest 

 "Sea-Hog," " Sea -Pig," or "Herring-Hog" of our fisher- 

 men, Me&rschwein of the Germans, corrupted into the French 

 " Marsouin," and also " Porcpoisson," shortened into " Porpoise." 



The difficulty that might be suggested in the derivation 

 of the Cetacea from the Ungulata, arising from the latter 

 being at the present day mainly vegetable feeders, is not 

 great, as the primitive Ungulates were probably omnivorous, 

 as their least modified descendants, the pigs, are still ; and 

 the aquatic branch might easily have gradually become more 



