208 BIRDS. 



the greater numljer profit, by a conformation so favourable to a vertical 

 position, to climb trees.* 



Each of these orders is subdivided into families and genera, and prin- 

 cipally from the conformation of the beak. But these different groups 

 frequently pass into each other by almost imperceptible gradations, so that 

 there is no other class in which the genera and sub-genera are so diffi- 

 cult to limit. 



ORDER I. 



ACCIPITRES, Lin. 



Birds of prey are known by their hooked bill and talons, powerful wea- 

 pons, by means of which they pursue other birds, and even the weaker 

 quadrupeds and reptiles. They are among birds what the carnivora are 

 among quadrupeds. The muscles of their thighs and legs indicate the 

 strength of their claws ; their tarsi are rarely elongated ; they have, all, 

 four toes; the nail of the thumb and that of the internal toe are the 

 strongest. 



They form two families, the diurnal and the nocturnal. 



The eyes of the diurnal birds of prey are directed sideways ; they have 

 a membrane called the cera, covering the base of the bill, in which the 

 nostrils are pierced ; three toes before, one behind, without feathers, the 

 two external ones almost always united at their base by a short membrane ; 

 the plumage dense, the quills strong, and great power on the wing. Their 

 stomach is nearly altogether membranous, their intestines of but small ex- 

 tent, their caecum very short, their sternum broad and completely ossified 

 in order to give more extended attachments to the muscles of the wings, 

 and their fourchette semicircular and widely separated, the better to resist 

 the violent motions of the humerus necessary to a rapid flight. 



Linnaeus comprehended them all under two genera, which are so many 

 natural divisions, the Vultures and the Falcons. 



VuLPUR, Lin. 



The Vultures have eyes even with the head, and reticulated tarsi, that 

 is, covered with small scales : an elongated bill, curved only at the end, 

 and a greater or less portion of the head, or even of the neck, divested of 



* From my first Tableau Elementaire, in 1798, I was obliged to suppress the Lin- 

 naean order of the Picae, which has no one determined character, llliger and the 

 greater number of recent ornithologists hav« assented to this suppression. 



