Ill INTRODUCTORY OBSERVATIONS 



Unless these affinities, which I have fully detailed, can be disproved 

 or explained by some other mode of reasoning, it seems to me im- 

 possible to arrive at any other conclusion *. 



Such are the principles of natural arrangement discoverable by 

 analysis, which more or less pervade the entire order of Perching 

 Birds. Aware that they are, in a great measure, opposed to every 

 theory yet started upon the subject, I have been anxious to establish 

 them by facts which are incontrovertible, and by arguments founded 

 not merely upon structure, but upon every circumstance, even the 

 most trivial, that is yet known of the economy of the birds themselves. 

 It is with these facts, and with these inferences, that such naturalists 

 as wish to establish other conclusions must deal. 



It cannot be too often repeated, that science has nothing to do with 

 mere opinions, or with abstract reasoning. Authentic facts and just 

 inferences, the former capable of being verified, and the latter founded 

 exclusively upon analysis, and in unison with some general harmony 

 of creation, are the only arguments which will possess any permanent 

 influence. 



The truth or the fallacy of these opinions must therefore entirely 

 repose upon the proofs here adduced ; for although similar results have 

 attended the investigation of other departments of nature, these 

 results have not yet been laid before the public in detail f , and conse- 



* Recent investigations in another department of Zoology, more abundant in forms and species 

 than that of the class Aves, lead me strongly to suspect the existence of another property in natural 

 groups, which at present I shall merely state as an hypothesis. It is the union of the most aberrant 

 group in one circle, with the most aberrant in the next ; so that in a diagram of the Order Insessores, 

 formed either on Mr. Macleay's plan of five circles, or of mine upon three, one circle would unite alt 

 the Tenuirostral types, another the Fissirostral and Scansorial, and a third the typical and sub-typical. 

 The whole would thus be represented by three great circles, one within the other, and this without 

 the least derangement of the series here exhibited. It must, however, be premised, that this principle 

 cannot be clearly traced in Ornithology, because the Tenuirostral or Grallatorial groups are remark- 

 ably deficient in their numerical contents. In Entomology, the very reverse of this appears to be the 

 case ; and it is there, if my suspicions are well founded, that it may probably be detected. 



t The essential characters of several of the groups in Conchology, slightly mentioned in the two 

 volumes of ' Zoological Illustrations,' new series, now in course of publication, depend upon the same 

 laws. I may also be allowed to cite, in corroboration of the theory now advanced, " The principles 

 which appear to regulate the geographic distribution of man and of animals," as detailed in the ' En- 

 cyclopedia of Geography,' p. 245 — 266, the proofs sheets of which are now before me. So far as 

 concerns the variation of Man, I feel all the confidence that can result from being supported by such 

 philosophers as Covier and Blumenbach. On this point the theory is theirs,not mine. (July 1831.) 



