£ 
280 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 Znsessores, 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 Hore Entomologice; 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. 
