AVES. 



71 



sternum flat, without ridge ; pectoral muscles weak ; those 

 of the thigh and leg enormously thick ; the thumb always 

 deficient. Two genera. 



Genus Struthio, Lin. Ostrich. 



Beak depressed horizontally, of moderate length and blunt 

 at the end ; tongue short, and rounded like a crescent ; eye 

 large, the lid fringed with lashes. Legs and tarsi very long. 

 Rapidity of course greater than that of any of the Mammalia; 

 feet furnished with two or three toes, either all with nails or 

 none ; crop enormous, followed by a considerable sac between 

 it and the gizzard. Africa and South America. 



Genus Casuarius, Briss. Cassowary. 



Wings still shorter than those of the Ostrich, and totally 

 useless even in running. Feet with three toes all furnished 

 with nails ; barbs of the feathers so scantily furnished with 

 barbulse, that at a distance they appear covered with pendent 

 hair. India and New Holland. 



FAMILY IL PRESSIROSTRES. 



Long legs, without thumbs, or with one so short as to be 

 unable to reach the earth; beak of moderate size and suffi- 

 ciently strong to penetrate the earth in the search for Worms. 

 Three remarkable genera. 



Genus Otis, Lin. Bustard. 



Beak nearly straight, and compressed; wings short; toes 

 short and bordered with membranes; no thumbs. 



Genus Charadrius, Lin. Plover. 



Beak moderate, enlarged at the end, and the nostrils occu- 

 pying one half to two-thirds of its length ; no thumb. 



Genus Vanellus, Bechst. Lapwing. 



Same beak as the Plover, but a small thumb. 



FAMILY III. CULTRIROSTRES. 



Beak thick, long and strong, generally trenchant and 

 pointed. Three tribes. 



