•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 Picidaz 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 Picida? 

 follow the Psittacidaz, and these latter being succeeded by the creepers 

 (Certhiadce,) the cuckoos (Cuculidce,) and the toucans (Rampkasli- 

 da.) 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, — a 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 (Certhiada?,) 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, 

 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 Tenuiroslres, and the very long tail-covers 

 of the Grallatores. Lastly, the Ramphastidas 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 

 to the Fissirostres in the circle of the perchers, and to the Natalores 

 in that of the orders of birds, is not only unequivocal, but most strik- 

 ing and remarkable. 



I shall now point out in what manner I conceive these five sub- 

 * Classification of Animals. 



