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 douSt 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 Wisdom 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 Psittacidce and the Picidce. 



