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X'ivable attribute of this archetypal form which is habitually realiscLl 

 by actual vertebrae. The alleged group of true vertebral elements 

 is not distinguished in any specified way from bones not included in 

 it. Its members have various degrees of inconstancy ; are rarely 

 all present together ; and no one of them is essential. They are 

 severally developed in no uniform way : each of them may arise 

 either out of a separate piece of cai'tilage, or out of a piece con- 

 tinuous with that of some other element ; and each may be ossified 

 from many independent points, from one, or from none. Not only 

 mav their respective individualities be lost by absence, or by con- 

 fluence with others ; Ijut they may be doul)led, or tripled, or halved, 

 or may be multiplied in one direction and lost in another. The en- 

 tire group of typical elements may coalesce into one simple bone 

 representing the whole vertebra ; and even, as in the terminal piece 

 of a bird's tail, half-a-dozen vertebrae, with all their many elements, 

 may become entirely lost in a single mass. Lastly, the respective 

 elements, when present, have no fixity of relative position : sundry 

 of them are found articulated to various others than those with 

 which they are typically connected ; they are frequently displaced 

 and attached to neighbouring vertebrae ; and they are even removed 

 to quite remote parts of the skeleton. It seems to us that if this 

 want of congruity with the facts does not disprove the hypothesis, 

 no such hypothesis admits of disproof. 



Unsatisfactory as is the evidence in the case of the trunk and 

 tail vertebrpe, to which we have hitherto confined ourselves, it is far 

 worse in the case of the alleged cranial vertebrae. The mere fact 

 that those who have contended for the vertebrate structure of the 

 skull, have ditfered so astonishingly in then- special mterpretations 

 of it, is enough to warrant great dou'it as to the general truth of 

 their theory. From Professor Owen's history of the doctrine of 

 general homology, we gather that Dumeril wrote upon " la tete 

 consideree comme une vertebre ;" that Kielmeyer, " instead of 

 calling the skull a vertebra, said each vertebra might be called a 

 Bkull;" that Oken recognized in the skull three vertebrae and a 

 rudiment ; that Professor Owen himself makes out four vertebra? ; 

 that Goethe's idea, adopted and developed by Cams, was, that the 

 skull is composed of six vertebrae ; and that Geoffroy St. Hilaire 

 divided it into seven. Does not the fact that different comparative 

 anatomists have arranged the same group of bones into one, tliree, 

 four, six, and seven vertebral segments, show that the mode of de- 

 termination is arbitrary, and the conclusions arrived at fandful .^ 

 May we not properly entertain gi-eat doubts as to any one scheme 

 being more vahd than the others ? And if out of these conflicting 

 schemes we are asked to accept one, ought we not to accept it only 

 on the production of some thorougltlv conclusive proof — sonif 



