38 A BOOK OF 'WHALES 



neck vertebrae to the necessity for holding up the 

 heavy head of the great whales. And it is un- 

 doubtedly a fact that in the Right whales and in 

 the huge -headed Physeter these peculiarities are 

 seen in as exaggerated a form as anywhere. On 

 the other hand, we must set against this the fact that 

 in the great Rorquals there is usually a freedom 

 between these vertebrae, which, in some species, is 

 complete. A further consideration of the variations 

 in the degree of fusion between the cervical vertebrae 

 seems to point to the conclusion that the peculiarity 

 is one which is, as it were, gaining ground, for the 

 Platanistidae, which some other considerations lead 

 us to regard as among the most primitive of existing 

 Cetaceans, have all these vertebrae quite free ; between 

 this extremity and that offered by the Right whales 

 are almost every possible step in the fusion of the 

 individual bones ; some, for instance, have two, three, 

 etc., fused and the rest free. 



In fact, it seems difficult to explain this anomalous 

 state of affairs by any adaptation to a particular need. 

 Nor is it possible to seek for any explanation of the 

 peculiarity by looking for its occurrence in any 

 possible allies of the whales. If it were suggested 

 that the Sirenia are creatures which are, so to speak, 

 on the way to become whales which connect the 

 whales with the terrestrial Ungulates- it might be 

 urged that here, at any rate, is a trace of the same 

 fusion of the neck vertebrae, for in the Manatee two 

 of these vertebrae are thus fused. But we have, on 

 the other hand, the Armadillos, where the same thing, 



