ORDER FIFTH. 



ZYGODACTYLI. (Birds with the toes disposed in 

 opposite pairs.) 



The bill of various forms, but more or less arched and 

 much hooked, — often also straight and angular (in the 

 second family or sub-order.) The toes are always di- 

 rected two backward and two forward, the hind exterior 

 toe, however, often reversible. 



This order contains birds which have the power of 

 directing at will the outer toe backward or forward ; it 

 also contains a considerable number (or subordinate 

 family) which retain habitually the digits in pairs. This 

 conformation, affording a more solid manner of attach- 

 ment, furnishes the means for clinging to and scaling the 

 trunks and branches of trees ; others also make use of 

 this support advantageously for the purpose of prehension 

 (as the Parrots.) The European and North American 

 genera of this order subsist principally upon caterpillars, 

 worms, and the larvae of insects ; other exotic genera, 

 with a thick and curved bill, give a preference to soft 

 fruits, while others, with very strong and hooked bills, 

 derive their subsistence from kernels and nuts. The 

 greater number of those birds which have the toes dis- 

 posed in pairs, nest in the natural cavities of old trees, 

 and some, by the aid of their cutting wedged, bills, form 



