266 FIRST PRINCIPLES OF NATURAL CLASSIFICATION. 
their introduction in this place would have extended 
our remarks to a volume, and have so embarrassed our 
definitions, that, although the adept could have under- 
stood them, the student would have been perplexed. 
When each class of animals, in the succeeding volumes 
of this series, comes to be treated of separately, we 
shall then, and then only, enter upon demonstration. 
CHAP. TE: 
THE FIFTH PROPOSITION CONSIDERED. — ON THE RELATIVE 
RANK OF THE DIFFERENT CIRCULAR GROUPS IN THE ANIMAL 
KINGDOM. —ON SPECIES AND VARIETIES. — ON THE MEANS 
THUS OFFERED BY THE LAWS OF NATURAL ARRANGEMENT, 
FOR THE VERIFICATION OF GROUPS. —=FAMILIAR ILLUSTRA- 
TION OF THE PRINCIPLES OF CLASSIFICATION HERE DE- 
VELOPED. — QUESTIONS ON ANALOGICAL COMPARISONS. 
(324.) Tue fifth and last proposition with which we 
commenced this part of our volume, is as follows : — 
That the different ranks or degrees of circular groups in 
the animal kingdom are nine, each being involved within 
the other. The full demonstration of this law would 
obviously require an analytical exposition of the whole 
number of circles here mentioned ; which, to do tho- 
roughly, would in itself require a volume. We can, 
therefore, only offer presumptive evidence on its appa- 
rent accuracy, drawn from facts, observations, and in- 
ferences already before the public, and which have 
remained unquestioned. Species and varieties will next 
claim our attention: and, finally, we shall conclude 
this division of our volume with a brief enumeration 
and a familiar application of those laws by which na- 
tural groups are to be verified. 
(325.) We have seen that the whole animal kingdom 
is composed of an infinite number of circles, touching 
