268 FIRST PRINCIPLES OF NATURAL CLASSIFICATION. 



more definite than her species; and it must conse- 

 quently follow, that, as they are of different ranks, 

 there must he some prevalent number of these ranks. 



(327.) Upon this abstruse question little has been 

 said or written, although all naturalists have long been 

 accustomed to use different names to denote the relative 

 value of their divisions. Mr. MacLeay, looking to annu- 

 lose animals alone, in speaking of the rank of the genus 

 Scarabteus, seems to think that there are eight different 

 descriptions of circular groups ; but this opinion is the 

 result, as he himself premises, more of conjecture than 

 of analysis. It is, nevertheless, much nearer the truth 

 than could have been supposed ; for if he had been 

 aware that sub-genera are likewise circular, the number 

 would have been nine. Now, this is precisely the very 

 highest number of circular groups, differing in value 

 each from the other, that can be traced in ornithology; 

 and in the typical divisions of the order Lepidoptera 

 among insects. This fact, in both instances, rests not 

 upon theoretical supposition, but upon demonstrative 

 analysis. We mean not to assert that there can be 

 no divisions of sub-genera, which may not, in them- 

 selves, be circular ; because it seems to be a law of 

 nature to carry this principle into her I6west assem- 

 blages ; but hitherto we have not clearly detected any 

 sub-genus of this description. Should the divisions of 

 sub- genera, in such cases, really be, in themselves, dis- 

 tinct circles, they may be detected, probably, in the 

 family of Carabida Sw., composed of the Carabidce and 

 HarpalidtB of authors. 



(328.) The animal kingdom, then, may be pre- 

 sumed to contain nine different ranks or gradations of 

 circular groups, commencing with the highest, and ter- 

 minating with the lowest assemblages. These groups 

 have received the following names, which at once indi- 

 cate their relative value: 1. Kingdom; 2. Sub- 

 kingdom ; 3. Class ; 4. Order ; 5. Tribe ; 6. Family ; 

 7. Sub-family ; 8. Genus ; 9. Sub-genus. This latter 

 is the lowest description of circular group hitherto de- 



