336 



NORTH AMERICAN BIRDS. 



of the crop. Although not truly gregarious, they assemble in multitudes 

 where food is plenty, and some species breed in communities. When gorged, 

 they appear heavy and indisposed to exertion, usually passing the period of 

 digestion motionless, in a listless attitude, with their wings half spread. But 

 they spend most of the time on wing, circling high in the air ; their flight is 

 easy and graceful in the extreme, and capable of being indefinitely pro- 

 tracted. On the ground, they habitually walk instead of progressing by 

 leaps. Possessing no vocal apparatus, the Vultures are almost mute, emitting 

 only a weak hissing sound." (CouES.) 



The Cathartidce all belong to the tropical and warm temperate portions of 

 the continent, only one species {Rhinogryjphus aura) extending its range as 

 far as the border of the colder regions. The famous Condor {Sarcorhamplvus 

 gryjilius) of the Andes and the equally large California species {Pseudogry- 

 phus californianus) are among the largest birds of flight in the world, being 



exceeded in size by none, and rivalled 

 but by one or two of the Vultures 

 of the Eastern Hemisphere. 



The following diagnoses based upon 

 the external structure are sufficient 

 to characterize the very well-marked 

 genera and subgenera of this family. 

 The distinctive osteological characters 

 which accompany tliese external fea- 

 tures afford still more decided differ- 

 -_ ences, and are illustrated Ijy the fig- 

 ures. 



S. gryphus, cf , Chile. ^ nat. size. 



S. papa, 9 , Mazatlan. >.( nat. size. 



Genera and Subgenera. 



A. Crop naked. Male with a fle.shy crest, or lobe, attached to the top of the 

 cere. Bill very robust and strong, its outlines very convex; cere much shorter 



than the head. 



1. Sarcorhamphus. Entire neck bare; nasal cavity entirely open; pos- 

 terior claw very thick and strongly curved. Tail even. 



Sexes different, the female lacking any fleshy caruncles, or appendages, 

 on the head and neck. Frontal lobe, or fleshy crest of male, extending 

 from the anterior border of the cere to the middle of the crown ; throat 

 with a median wattle, or " dewlap " ; side of the neck Avith a somewhat 

 convoluted or twisted caruncle, extending from the side of the occiput 



