2o FIRST PRINCIPLES OF NATURAL CLASSIFICATION, 



however, at present dilate, but merely call the attention 

 of the philosophic enquirer to what we have already 

 stated elsewhere. " Recent investigations in another 

 department of zoology, more abundant in forms and 

 species than that of the class AVES, leads 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 all the Tenuirostral types, an- 

 other the fissirostral and scansorial, and a third the 

 typical and sub-typical. The whole would thus be re- 

 presented 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 

 remarkably 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 this abstruse property of the natural system may 

 hereafter be more especially detected."* 



(291.) Having now sufficiently explained the various 

 relations of affinity which animals bear to each other, the 

 reader will be better prepared to understand the principle 

 of the proposition more immediately before him ; namely, 

 the analogical or symbolical representation of the contents 

 of one circle with those of the contents of all circles in 

 the animal kingdom. This may be distinguished as the 

 law of representation. This property of natural groups 

 was first intimated in the Horce Entomologies; but it was 

 only partially employed as a verification of the groups 

 therein mentioned, nor was it at all suspected to hold 

 good throughout nature. It was perceived in theory; 

 but, the laws by which it was regulated not being then 



* North. Zool. preface. 



