128 
ON THE CLASSIFICATION OP BIRDS. 
general structure, that the 
unprejudiced zoologist im- 
mediately perceives they 
form a truly natural group. 
(141.) The economy of 
these birds, so far as they 
have been observed by tra- 
vellers, is directly against 
the theory of their being likened to the gallinaceous order. 
The Chili plant-cutter builds on the highest trees ; while 
the African touracco {Corythaix 111.), whose manners 
particularly engaged the attention of the indefatigable Le 
VaiUant, perches only at the extremities of the highest 
branches of the forest trees, rarely descending sufficiently 
low to come within gunshot. As to the anatomic^ 
structure of the touraccos, the admission of M. Cuvier, 
that they only present “ quclque anahgie avec les gal- 
linaces for that the external toe is versatile, and they 
have not the notched sternum of those birds, is directly 
opposed to the theory of these birds leading to the Gal- 
linacea, and if this needed further confirmation, it is cor- 
roborated by a remark by Mr. Y arrell, who dissected a 
touracco, living some time in the Zoological Gardens.* 
(142.) It is clear, from the foregoing remarks, that 
the apparent disproportion of size in the birds we asso- 
ciate in this group is not greater than what would be 
expected ; and, indeed, were it otherwise, we might 
fairly entertain doubts whether our arrangement was 
correct. Between a family of small birds like the Frin- 
gilMa, and another of such large ones as the liuccridce, 
there should be a graduated scale, or at least some in 
the intervening group should be small, some middle- 
sized, and some large. Now, this gradation actually takes 
place in the birds composing our present family. The 
size and entire aspect of Phytotoma is that of a hul- 
finch. Coliug also, in this respect, as well as in its bill, 
unites the character of a Fringilla and a Mvsophaga. 
Hyreus, a bird we have not seen, and of which no speci- 
» ZooL Journ. No. xv. i>, 319. 
