O29 ON SYSTEMATIC ZOOLOGY. 
entomologists) so confident in their conviction of the truth 
of circular affinities, and yet so unconsciously regardless 
of those principles which must establish this theory in the 
minds of acute reasoners. The proof of a circle of affinity, 
as laid down by its discoverer, rests, in the first instance, 
upon its complete analysis ; and, secondly, in its con- 
tents intimately and regularly corresponding in analogy 
with the contents of a neighbouring circle. There may 
be seven, ten, twenty, or fifty natural orders, for what 
we know, and they may possibly be circular, and there- 
fore natural; but with the above conditions of a circle 
before us, we must ever withhold our belief-in such di- 
visions, until they rest upon a more solid foundation 
than arbitrary opinion. Although somewhat backward in 
viewing zoology as but a branch of physical science, 
we are happily so far advanced in its philosophy, as to 
consider facts more weighty than assertions, and cautious 
induction more valuable than hypothesis. If, then, the 
number seven is to be substituted for that of five, let it 
be made out analytically and analogically in any two 
groups out of the many which have been assumed as 
“* natural,” and we will venture to predict that the 
learned author of the Hore Entomologice would be one 
of the first whe would proclaim the truth of the demon- 
stration. We offer these observations generally, and as 
equally applicable to any determinate number which 
may be thought the true one of nature. 
(272.) It has been said, in reference to the quinary 
theory, that in most cases the number of divisions in a 
natural group is five, but that in many instances there 
appear to be as many as seven. Now, this may be very 
true in one sense, and very erroneous in another. 1. If 
a circular group is to be divided merely according to the 
fancy of the divider, or according to those marks or 
characters which he thinks most important, without re- 
ference to any other considerations, it is obvious that 
scarcely two persons will agree in the number they 
eventually fix upon: one may make three, another five, 
and another seven. But then comes the first test of accu- 
