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now been devoted, almost unceasingly, to this investigation; and
although I have found it impossible in every instance to enter into
details, I now venture to lay the results before the world, considering
that a more appropriate channel for such communication could not be
chosen than this : being the first zoological work ever published under
the immediate authority of the British Government.
The object of the introductory observations to each family of the
order T nsessores, is to demonstrate the following peculiarities in
natural arrangement. These I shall briefly state as propositions.
1. Emery natural series of beings, in its progress from a given point, either actually
returns, or evinces a tendency to return, again to that point, thereby forming
a Circle.
2. The contents of such a Circle or Group are symbolically represented by the
contents of all other Circles in the same class of animals ; this resemblance
being strong or remote, in proportion to the proximity or the distance of the
groups compared.
3. The primary divisions of every natural Group, of whatsoever extent or value,
are t h r e e , each of which forms its own Circle.
1. Little need be said on the first proposition, since it is in complete
accordance with the theory supported by MM. Macleay, Fries,
Agardh, Oken, &c. I have merely modified it for the purpose of
showing that, strictly speaking, every growp is not a circle, since in
many which, by the theory of representation, can be proved to be
natural, the circle is incomplete, either by the extinction or by the
non-discovery of certain types. The aberrant group of the class Aves,
of the order Raptores, and of the family of Picidee, are all striking
examples of this truth.
2. This, which may be termed the theory of representation, was
this order. But it should not have been concealed that the merit of having first united the Pajseres
and the Picte belongs to M. Vieillot, and not to the writer in the Lmnsean Transactions. So far
back as the year 1816, M. Vieillot named this order Sylmcola. See his Analyse Otm., p. 25.
first promulgated in the Hors Entomologies, where it has been extensively
applied, and the author has shown its existence both in some
of the highest and in one of the lowest groups of vertebrated animals :
yet nowhere can I perceive that it has been declared—what I think
it to be-—the only certain test of a natural group. Circles may be,
and have been, formed with such a deceitful appearance of following
nature, that the most eminent and the most cautious have been led
into a belief that they were strictly natural. If such a group is thought
to be complete or perfect, it is very well to say, put each of its divisions
to the test of returning into itself*, and the fallacy will be discovered;
but among groups of a certain value, genera and sub-families more
particularly, there is not one in three that can be so tested. This
inability partly arises from our superficial acquaintance with forms,
and partly, as we believe, from there being many real gaps in the
chain of continuity. Without, therefore, some other test for a natural
group, than the mere circumstance of its returning into itself, or even
its simple parallelism with a contiguous group, I consider demonstration
not to have been attained. The theory of representation thus
steps in, and at once dispels the illusion, or demonstrates the correctness
of the series. In the sub-families of Myotherinee and Parians, I
have endeavoured to exemplify this principle of the natural system
in all its bearings.
3. The results that have attended my analysis of every natural
group hitherto investigated, lead me to differ in the onset from all
who have adopted the quinarian system. And so far as regards the
order of Insessores among birds, I have endeavoured to shew that
the primary circles of each group are invariably three. These I
have denominated—i. The typical; ii. The sub-typical; and iii. The
aberrant. Mr. Macleay, on the contrary, considers that every group
is first resolvable into five minor groups, two of which he terms
normal, and the other three aberrant. I know not why this talented
writer should have chosen to have used this latter mode of division,
which is binary, and but ill calculated, as it appears to me, to express
his own definition of a natural group. Neither he, nor M. Fries,
* Mr. Macleay’s Letter to Dr. Fleming, p. 33.