258 FIRST PRINCIPLES OF NATURAL CLASSIFICATION. 
which decorate the head. If we went through the 
whole class of birds, and selected those, beginning with 
the peacock, wherein the tail was most conspicuous, 
either for its size, its singularity, or for the beauty of 
its colours, we should, unknowingly, fix upon those 
birds which analysis has already demonstrated to be ra- 
sorial types. The same result would attend a similar 
selection of quadrupeds, and of winged insects. All these, 
collectively, would furnish many hundred proofs by 
which the uniformity of this type is preserved. Ap- 
pendages to the head, whether in the shape of horns, 
crests, or fleshy protuberances, are no less a prevalent 
character of the type now before us. Among birds, 
indeed, we scarcely know of more than two or three 
groups furnished with crests, which do not appear to be 
rasorial types ; and this very circumstance is sufficient 
to raise a doubt on their real denomination. But it 
seldom happens that both these peculiarities are united 
in the same group. Nature will sometimes indicate her 
types by two only of its leading characters, while she 
withholds a third, in order to bestow it, in its full de- 
velopement, upon another group modified upon the same 
general principles. Thus we see that the horse, one of 
the types of the rasorial order of ungulated quadrupeds 
(Ungulata), is superior to all the Mammalia in the 
beauty and elegance of its tail: but then this noble 
animal is destitute of another indication of its type; for 
the head is without either horns or protuberances: 
these, however, are bestowed upon the ruminants, be- 
longing to the same circle, who, on the other hand, are 
destitute of the flowing tail of the Solipedes. We 
thus see how two of the typical characters of the raso- 
rial structure is distributed between two groups*, which, 
nevertheless, collectively belong to the same order. 
This, in fact, seems to be one of the principles by 
which Creative Wispom has produced such infinite va- 
riety in His works ; for if, in reference to the horse and 
* This is still more strongly exemplified in the two primary groups of 
the Scansores —the Pstitacide and the Picide. 
