SOME INTERNAL STRUCTURES 



39 



precisely, occurs. And even in another group of 

 vertebrates altogether, the Hornbill offers an example 

 of a bird in which two of the cervical vertebrae are 

 fused. 



We shall deal presently with some facts in which 

 the Dugongs and Manatees resemble the whales, but 



FIG. 8. CERVICAL VERTEBR/E OF RIGHT WHALE. 



(From van Beneden and Gervais.) 



this view of the relationships of the whales is not 

 one which at the present day commends itself to 

 naturalists. It is a curious fact, however, that one 

 of the most remarkable peculiarities of one of these 

 Sirenia, the Manatee, i.e., the dropping of one 

 cervical vertebra, already referred to, is hinted at 

 in certain whales. The late Dr. Gray used as a 

 specific, and even as a generic, character the fact 

 that in some whales the first rib is a double structure, 



