218 On the Natural History of 
found in any other yet published, for the rank of each group in the 
three columns is so preserved, that what is typical in one is also 
typical in the two others. Thus, for instance, the Picidce or wood- 
peckers, which are the most perfect of all the climbers, are seen to 
represent the Conirostres, the most perfect of the perching order, 
and also the Insessores, which in like manner is the most perfect in 
the class of AVES. These analogies can be traced, in like manner, 
transversely, and arise as it were incidentally, without any derange- 
ment of the perpendicular series of affinities, by which the Picidce 
follow the Psittacidce, and these latter being succeeded by the creepers 
(Certhiadce,) the cuckoos (Cuculidce,) and the toucans (Ramphasti- 
dce.) The affinities, in short, as expressed in the above table, are 
perpendicular, and analogies transverse. As some of these latter 
are very curious, we shall here notice them. Every one must be 
struck with the intimate resemblance which the bill of the parrots 
has to that of the shrikes, among the Dentirostres , and to the hawks, 
among the Raptores y *& resemblance which led to the old artificial 
arrangements, wherein the two groups are made to follow each other. 
Quitting these, we have the conic lengthened bill of the wood- 
peckers, representing the Conirostres in one column, and the In- 
sessores in the other. The creepers (Certhiadce,) as every one knows, 
are eminently scansorial birds, although they have three toes for- 
ward, and one backward, like the Rasores, and in both the tail is 
unusually developed, although in different ways. The Cuculidce y 
as already demonstrated, are the most aberrant group of the whole, 
as this denomination implies that they are the most imperfect clim- 
bers. This latter conclusion, which we deduct theoretically from the 
situation we assign to this family, is borne out by the details al- 
ready given. These birds, in fact, may be said rather to run than 
climb among the horizontal branches of trees, as the Grallatores are 
the swiftest runners on the ground ; the cuckoos, moreover, have 
the very short feet of the Tenuirostres, and the very long tail-covers 
of the Grallatores. Lastly, the Ramphastidce or toucans represent 
the natatorial type, the chief characteristics of which, as more fully 
explained elsewhere,* is great bulk, a large head, wide mouth, 
short tail, and imperfect feet : now all these peculiarities distinguish 
'the toucans from the rest of the Scansores. and thus their analogy 
O J 
to the Fissirostres in the circle of the perchers, and to the Natatores 
in that of the orders of birds, is not only unequivocal, but most strik- 
ing and remarkable. 
1 shall now point out in what manner I conceive these five sub- 
* Classification of Animals. 
