Ml'. A. II. Wallace on the Natural Arrangement of Birds. 209 



of forms must have intervened to have filled up the chasms, and 

 formed a complete series presenting a gradual transition from 

 one to the other. The differences in the form of the bill have 

 already been alluded to, but those of the tongue are perhaps still 

 more extraordinary ; the fleshy tongue of the Parrot, the barbed 

 extensile spear of the Woodpecker, the short horny tongue of 

 the Cuckoo, and the long and slender feathered tongue of the 

 Toucan, vvould seem rather to belong to birds most remote from 

 each other, than to those for whom we can find no nearer allies. 

 We should be inclined to consider therefore that they form 

 widely distant portions of a vast group, once perhaps as exten- 

 sive and varied as the whole of the existing Passeres. 



Notwithstanding the difference of their food, it is evident that 

 the Cuckoos and the Toucans approach more closely to each 

 other than to the others. Their legs are longer, and they con- 

 sequently hop, which the other two never do. Their bills are 

 similar in form, their plumage is in both much more loose than 

 either in the Parrots or the Woodpeckers, which again, in these 

 peculiarities in which they agree, to some extent approach each 

 other. We would place therefore the Parrots and the Wood- 

 peckers at one extreme of the group, and also considerably re- 

 moved from each other, while the Toucans and Cuckoos, rather 

 nearer together, should be placed at the other extreme. 



The Barbets [Bucconidce of Lesson and Bonaparte, CapitonincB 

 of G. 11. Gray) have also been always included amongst the 

 Climbers, but their place has been so often varied and their affini- 

 ties so much misunderstood that they require a separate con- 

 sideration, especially as in the systems of Swainson and Gray 

 they have been considered as a subfamily of Picida, and have 

 therefore not appeared among the families of the Scansores. The 

 only ground for placing them with the Woodpeckers appears to 

 have been that some African species do cling against and peck 

 at trees something in the manner of those birds. Their whole 

 structure however is totally opposed to their being thus placed. 

 In their feet, wings, and the form of the whole body they much 

 more nearly resemble the Toucans. The texture of their 

 feathers, their broad, angular and weak skulls also resemble 

 them, and are strikingly dissimilar to those of the Woodpeckers. 

 From my own observations too, I can assert that, in the habits 

 both of the South American and of the Eastern species, they 

 resemble the Toucans more closely than any other birds ; and 

 Le Vaillant makes the same observation with regard to the African 

 species. Besides, the grand characteristic of the Woodpeckers, 

 the barbed and extensile tongue, which exists equally in the Yunx 

 and Pieumnus, is totally absent in the Barbets, while their bill is 

 of quite a different type of form, much more nearly approxi- 



Ann.^ Mag. N. Hist. Ser. 2. Vol. xviii. 14 



