AVES. 225 



Each of these orders is subdivided into families and genera, 

 and principally 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 difficult to limit. 



ORDER I. 



ACCIPITRES, Lin. 



Birds of prey are known by their hooked beak and talons, 

 powerful weapons, with 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 beak, in which the nostrils are pierced ; three toes before, 

 one behind, without feathers, the two external ones almost 

 always united at 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 extent, their csecum very short, their sternum broad 

 and completely ossified in order to give more extended attach- 

 ments to the muscles of the wings, and their fourchette semi- 

 circular and widely separated, the better to resist the violent 

 flexions 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. 

 Vol. I. 2 D 



