﻿136 



ON THE CLASSIFICATION OF BIRDS. 



shorter than the tarsus. It is only, however, in the 

 Australian genus Climacteris that this excessive deve- 

 lopment of the 

 posterior toe is 

 at its maximum 

 (fig. 73. a): in 

 this genus, owing 

 to its enormous 

 claw, the hinder 

 far exceeds the 

 length of the 

 middle toe, and this latter is connected to the one 

 that is external, nearly to the end of its first joint 

 (b). To account for this extraordinary enlarge- 

 ment of the toes in all the preceding birds, it must 



be remembered 

 • that their faculty 

 of climbing is 

 entirely derived 

 from these mem- 

 bers ; they re- 

 ceive no assist- 

 ^ ance whatever 

 - from their tail, 

 ^ which is not 

 only destitute of naked points, but of all rigidity, 

 so that, as a means of support, it becomes quite use- 

 less. 



( 1 23.) Let us now see what further variations occur 

 in genera where some assistance must be derived 

 from the tail, a fact we gather from the feathers pos- 

 sessing different degrees of rigidity, without their being 

 absolutely stiff or terminating in naked points. The 

 genera whose tails are thus formed are Zenops (fig. 74.), 

 Anabates, Dendroma, part of Synallaocis, Oocyrhynchus, 

 and Buphaga. In the four first the tail, although pos- 

 sessing but a very slight degree of stiffness, is yet suf- 

 ficiently firm to give some aid to the bird in climbing, 



