2 BRITISH BIRDS. 



his ' Catalogue of the Birds in the British Museum/ enumerates nearly 

 400 species and subspecies, which he subdivides into 80 genera. In the 

 British Islands five-and-twenty species or more have occurred, belonging 

 to eleven genera, which may be distinguished as follows : 



a. Front of lower half of tarsus (as well as the sides and back) covered 



with small hexagonal reticulations, not feathered to the toes. 



a 1 . No true feathers on the crown of the head VTJLTUB. 



&'. Crown of the head covered with true feathers. 



a 2 . First primary much longer than the secondaries ; lores not 



feathered, but furnished with bristles. 

 a 3 . Tail even or slightly rounded. 



a 4 . Outer toe not reversible ; bill deeply notched .... FALCO. 



ft 4 . Outer toe reversible ; notch almost obsolete PANDION. 



ft 3 . Tail acutely forked ELANOIDES. 



b 2 . First primary about equal to the secondaries ; lores feathered PEBNIS. 



b. Front of tarsus feathered, or covered with broad transverse scales. 



c l . Tarsus less than one fourth the length of the tail MILVUS. 



d 1 . Tarsus more than one fourth the length of the tail. 



c 2 . Lower half of tarsus scaled in front and reticulated at the 



back HALIAETUS. 



d 2 . Lower half of tarsus either feathered in front or scaled at 

 the back. 



c 3 . Tarsus feathered in front to the toes AQUILA. 



d 3 . Lower half of tarsus scaled in front and at the back. 

 c 4 . Tarsus less than a fourth the length of the wing, 

 and less than half the length of the first primary. 

 a 5 . Tarsus thick ; circumference about one third 



of length BUTEO. 



6 5 . Tarsus slender ; circumference less than one 



fifth of length CIBCUS. 



J 4 . Tarsus one fourth or more the length of the wing, 

 and more than half the length of the first 

 primary ACCIPITEB. 



Genus VULTUR. 



The genus Vultur was established by Linnaeus in 1766, in his ' Systema 

 Naturae/ i. p. 122. In 1806 Dumeril separated the New-World Vultures, 

 restricting the genus Vultur to those of the Old World, but not designating 

 any type. Linnseus only knew two species of this genus, V. monachus and 

 V. percnopterus. As the former bird is undoubtedly the most typical 

 Vulture, its claim to be considered the type can scarcely be disputed. 



The species of Vulture which have been found in the British Islands are 

 easily separated from the rest of the Falconidse by the absence of true 

 feathers on the head, which is more or less naked, or covered with down 

 only. The front of the tarsus as well as its sides and back are covered 



