40 Mr. A. R. Wallace's Remarks on the Value of 



presents many important differences from those of all these 

 families, and fully bears out the isolation which their external 

 characters exhibit. It differs much from Megalama and Pteru- 

 glossus in its general form, as well as in details of structure, and 

 still more from Merops. It seems to approach the typical Pas- 

 seres more than either of the other groups to which M. Blanchard 

 compares it; but its peculiar pyramidal shape, so remarkably 

 narrowed at the anterior extremity, and its very short clavicles 

 distinctly separate it as a characteristic and isolated form. It 

 will, therefore, I think, be admitted that the affinities indicated 

 by the complete sternum and appendages are much more in 

 accordance with those derived from external form and structure, 

 and from habits and economy, than those which M. Blanchard 

 deduces from the body of the sternum alone. 



These remarks are made in no spirit of depreciation of this 

 very interesting and valuable work, but for the purpose of 

 showing that isolated characters may lead to erroneous conclu- 

 sions from whatever part of the organism they are chosen, and 

 that in this respect osteological have no positive superiority over 

 external characters. M. Blanchard tells us, in the introduction 

 to this first instalment of his work, that he proposes to examine 

 successively each separate part of the bird's skeleton. His future 

 researches may therefore seriously modify the conclusions he has 

 hitherto arrived at. I cannot but think, however, that he would 

 have produced a more satisfactory work, if he had based it upon 

 the comparison of the entire sternum, with its appendages 

 attached, and also on the cranium, these two parts being of the 

 greatest importance in classification. 



It has been well observed by Professor Owen that those parts 

 of an animal which have the least immediate connexion with its 

 habits and economy are exactly those which best exhibit deep- 

 seated and obscure affinities. The wings, the feet, and the beak 

 in birds may undergo the most extraordinary modifications in 

 the same group in accordance with differences of habits and of 

 external conditions, while at the same time such apparently in- 

 significant characters as the general colouring, the texture of 

 the plumage, the scaling of the tarsi, or the colour and texture 

 of the eggs remani constant, and reveal the true relations of 



