530 BRITISH BIRDS. 



Subfamily CORVIN^E, ok CROWS. 



The CrovYS and their allies are distinguished from all the allied sub- 

 families, except the Sylviiase, by having a spring moult as well as an 

 autumn one. Prom the latter subfamily they are principally distinguished 

 by their larger size ; the bill is generally large and conical, though in some 

 groups, as the Choughs, it is long and curved. The emargination of the 

 bill is sometimes well developed and sometimes quite obsolete. The wings 

 are rounded, the first primary being almost always more than half the 

 length of the second. The tail is subject to great variation, being some- 

 times short, sometimes long, sometimes even, and sometimes rounded, and 

 consists of twelve feathers. The feet and claws are strong, and the tarsus 

 is scutcllated. The Corvinse are cosmopolitan, and number about two 

 hundred species. About ten species are found in the British Islands, 

 belonging to six genera, which may be distinguished as follows : — 



a. Tail less tliau three fourths the length of the wing. 



ff\ Bill feathered to the base, but nostrils bare Ohiolus. 



6'. Bill feathered to the base and nostrDs covered with bristles, or 

 base of bill and nostrils bare. 

 U-. Bill black or browu. 



dK Throat spotted; tail black and white ~. . ... KucirnAG.v. 



J*. Throat unspotted ; tail black Couviis. 



})-. Bill I irange or yellow Pyhehocoeax. 



h. Tail more than three fourths the length of the wing. 



e\ Tail much graduated Pica. 



0}. Tail nearl}- even G.uieulus. 



Genus CORVUS. 



The genus Corom was established by Linnaeus in 1766, in his ' Sy sterna 

 Naturae,' i. p. 155. Since Linnaeus does not give us the slightest clue as 

 to which species he considers typical, we must fall back upon Brissou, 

 whose Corvus corvus is undoubtedly the Raven and the Corvus corax of 

 Linnseus, which we may accept as the type. 



