400 DR KNOX on the Dentition of the Dugong, and on the 



turalists. The Scapulae of the dugong, have no resemblance to 

 those of any of the Cetacea I have examined, but they approach 

 those of the walrus. The great strength of the zygomatic arch, 

 and, indeed, the whole anterior part of the body, shews the 

 natural affinity with the tribe of the walrus ; so that here, as in 

 so many other zoological cases, I fear it will be found that consi- 

 derations, drawn chiefly from external characters, lead only to 

 false conclusions. 



True Cetacea. 



We owe to Mr JOHN HUNTER most of the best made out ana- 

 tomical facts in the history of the Cetacea : above all, we owe to 

 him the history of their mode of dentition ; and the facts and ob- 

 servations, together with the conclusions drawn from them, have, 

 so far as I know, never been directly questioned by any one. Mr 

 HUNTER, I think, was the first to prove that, in their mode of 

 dentition, whales do not strictly resemble other mammalia. He 

 shewed, as far at least as the field of his inquiry extended, that 

 nothing that had been made out regarding the succession of the 

 teeth in the other mammalia, was at all applicable to the Cetacea. 

 In them we have no permanent teeth following milk-teeth, but 

 one set only which are at once temporary and permanent, that is 

 to say, the anterior ones, together with the small part of the jaw 

 containing them, are constantly worn away and lost during the 

 life of the animal, and these are replaced by others, which grow 

 up from behind, precisely as in the elephant. Now, I had 

 thought that this mode of dentition described by Mr HUNTER, 

 and which I had myself verified in a very considerable number 

 of the Cetacea, might, without venturing on a rash analogy, be 

 held as applicable to all the Cetacea ; but it would seem some 

 have thought differently, and, among these, the immediate sue- 



