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ON THE CLASSIFICATION OP BIRDS. 



sores with the Rasores, the hinder toe is nearly as long 

 as in the cuckows, and is considerably more developed 

 than in any other group of rasorial birds. We will say 

 nothing of the genera Megapodius, Palamedia, and 

 Menura, whose feet are well known to be enormous; or 

 of Opisthocomus , because specimens of these large and 

 rare birds are not upon our table. Confining ourselves 

 to the genus Penelope, we may remark that the toes, 

 considered by themselves, might be taken for those of a 

 cuckow, if the outer one was only versatile ; it is evident 

 also, from the structure of the claws, that these birds 

 are much more arboreal than their congeners, for their 

 claws are more curved ; and from their lateral, and not 

 horizontal compression, as well as from their acuteness, 

 we conclude that they are very little, if at all employed 

 in scratching the ground, their structure being similar 

 to those of perchers, and adapted only for clinging. The 

 foot, in fact, of the Penelope is not a rasorial, but an 

 insessorial foot, for it does not possess any one of the 

 rasorial characters. Even the hind toe, which, in all other 

 rasorial birds, is raised above the heel, is here placed 

 upon the same level as the anterior toes (fig> 84.). That 

 no ambiguity should rest on this fact, we beg to call the 

 ornithologist's attention to the particular species now 



before us, the P. aracuan of Spix (ii. pi. 74.), one of the 

 most common of the genus. How this remarkable forma- 



