ON' THE VERTEBRATE SKELETON*. 241 



directly opposed the idea of ' special homology ' being included in a higher 

 law of uniformity of type. 



Yet the attempt to explain, by the Cuvierian principles, the facts of special 

 homology on the hypothesis of the subserviency of the parts so determined 

 to similar ends in different animals, — to say that the same or answerable bones 

 occur in them because they have to perform similar functions — involve many 

 difficulties, and are opposed by numerous phsenomena. We may admit that 

 the multiplied points of ossification in the skull of the human foetus facilitate, 

 and were designed to facilitate, childbirth ; yet something more than such a 

 final purpose lies beneath the fact, that most of those osseous centres repre- 

 sent permanently distinct bones in the cold-blooded vertebrates. The cra- 

 nium of the bird, which is composed in the adult of a single bone, is ossified 

 from the same number of points as in the human embryo, without the pos- 

 sibility of a similar purpose being subserved thereby, in the extrication of 

 the chick from the fractured egg-shell. The composite structure is repeated 

 in the minute and prematurely-born embryo of the marsupial quadrupeds. 

 Moreover, in the bird and marsupial, as in the human subject, the different 

 points of ossification have the same relative position and plan of arrange- 

 ment as in the skull of the young crocodile, in which, as in most other rep- 

 tiles and in most fishes, the bones so commencing maintain throughout life 

 their primitive distinctness. These and a hundred such facts force upon the 

 equal and knowing anatomist the inadequacy of the teleological hypothesis 

 to account for the acknowledged concordances expressed in this report by 

 the term ' special homology.' If, therefore, the attempt to explain them as 

 the results of a similarity of the functions to be performed by such homo-' 

 logous parts entirely fails to satisfy the conditions of the problem ; and if, 

 nevertheless, we are, with Cuvier, to reject the idea of their being manifes- 

 tations of some higher law of organic conformity on which it has pleased 

 the divine Architect to build up certain of his diversified living works, 

 there then remains only the alternative that special homologies are matters 

 of chance. 



This conclusion, I apprehend, will be entertained by no reasonable mind ; 

 and reverting, therefore, to the more probable hypothesis of the dependence 

 of the special resemblances upon a more general law of conformity, we 

 have next to inquire, what is the vertebrate archetype ? The gifted and 

 deep-thinking anatomist, Oken, obtained the first clew to this discovery by 



on this subject. " It is not by any means our intention to engage our readers in discussing 

 all the conflicting and, sometimes, visionary opinions entertained by different authors re- 

 lative to the exact homology of the individual bones forming this part of the skeleton ; and 

 we shall, therefore, content ourselves by placing before them, divested as far as possible of 

 superfluous argumentation, Cuvier's masterly analysis of the labours of the principal inquiries 

 concerning this intricate part of anatomy." — p. 494. A later English author, who has em- 

 bodied a most valuable amount of careful and exact osteological observation in the article 

 " Zoology" of the ' Encyclopaedia Metropolitana' (4to, 1845), seems scarcely to regard even 

 the determination of special homologies as a necessary object of anatomical research. Thus, 

 in discussing the differences of opinion respecting the coracoid (fig. 5,4s). he says, " Bakker's 

 view, however, if it be absolutely necessary to hunt up analogies, seems more correct." — 

 p. 302. 



This reserve is, however, perhaps less obstructive to the philosophical progress of anatomy 

 and to the requisite resumption of original inquiry to that end, than the mere reproduction 

 of the transcendental views of others without criticism or attempt to explain or refute the 

 objections to such views which have been promulgated by so great authorities as Cuvier and 

 Agassiz. Thus Bojanus's 4-vertebral theory of the cranial part of the skull is adopted by 

 M. De Blainville (Osteographie, 4to) ; whilst Dr. Grant (Outlines of Comparative Anatomy, 

 8vo, 1835, p. 63) deems the composition of the skull, in fishes, to correspond nearly with 

 Geoffroy's theory of this part of the skeleton being composed of seven vertebrae, each con- 

 sisting of a body with four elements above and four elements below. 



