1024 ON FORM AND MECHANICAL EFFICIENCY [ch. 



extinct Zeuglodons are related to the old Creodont carnivores, and 

 thereby (though distantly) to the seals*; and it is supposed, but it 

 is by no means so certain, that in turn they are to be considered 

 as representing, or as allied to, the ancestors of the modern toothed 

 whales t. The proof of any such a contention becomes, to my 

 mind, extraordinarily difficult and complicated ; and the arguments 

 commonly used in such cases may be said (in Bacon's phrase) to 

 allure, rather than to extort assent. Though the Zeuglodons were 

 aquatic animals, we do not know, and we have no right to suppose 

 or to assume, that they swam after the fashion of a whale (any 

 more than the seal does), that they dived like a whale, or leaped 

 like a whale. But the fact that the whale does these things, and 

 the way in which he does them, is reflected in many parts of his 

 skeleton — perhaps more or less in all: so much so that the lines 

 of stress which these actions impose are the very plan and working- 

 diagram of great part of his structure. That the Zeuglodon has 

 a scapula Hke that of a whale is to my mind no necessary argument 

 that he is akin by blood-relationship to a whale: that his dorsal 

 vertebrae are very different from a whale's is no conclusive argument 

 that such blood-relationship is lacking. The former fact goes a long 

 way to prove that he used his flippers very much as a whale does; 

 the latter goes still farther to prove that his general movements 

 and equilibrium in the water were totally different. The whale 

 may be descended from the Carnivora, or might for that matter, 

 as an older school of naturalists believed, be descended fropa the 

 Ungulates; but whether or no, we need not expect to find in him 

 the scapula, the pelvis or the vertebral column of the lion or of the 

 cow, for it would be physically impossible that he could live the life 

 he does with any one of them. In short, when we hope to find the 

 missing links between a whale and his terrestrial ancestors, it must 

 be not by means of conclusions drawn from a scapula, an axis, or 



* See {int. al.) my paper On the affinities oi Zeuglodon in Studies from the Museum 

 of University College, Dundee, 1889. 



t "There can be no doubt that Fraas is correct in regarding this type (Procetus) 

 as an annectant form between the Zeuglodonts and the Creodonta, but. although 

 the origin of the Zeuglodonts is thus made clear, it still seems to be by no means 

 so certain as that author beheves, that they may not themselves be the ancestral 

 forms of the Odontoceti" (Andrews, Tertiary Vertebrata of the Fayum, 1906, 

 p. 235). 



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