PTEROCLID^. 495 



nude ; the wings long and pointed, with the first primary longest, 

 or the first and ^second nearly equal. The tail varies, being 

 short and slightly rounded in some, longer and graduated in 

 others, with the medial feathers greatly lengthened in several, 

 and much attenuated at the tips. The tarsus is short, rather 

 slender in most, always feathered in front; the toes are short, 

 either joined at the base by a small web, or soldered together. 

 The feathers of the lower back and rump are not lengthened, 

 and the clothing feathers are devoid, or nearly so, of the sup- 

 plementary tuft. 



The keel of the sternum is enormously developed, and the inner 

 emargination wanting, or represented by a small oval foramen, 

 as in Pigeons ; the sternum itself is very narrow, and contracted 

 in front : the furcula is short and wide, and does not possess the 

 medial appendage. In their internal anatomy, they closely re- 

 semble other Gallinaceous birds. 



The Sand-grouse or Rock-grouse, commonly called Rock- 

 pigeons in India, are birds of remarkably rapid and powerful 

 flight. They feed almost entirely on hard seeds, breed on the 

 ground, laying usually three or four dull greenish spotted eggs ; 

 and the young run as soon as hatched. They are peculiar to the 

 warmer regions of the Old World, being particularly abundant in 

 Africa, and in the desert regions of Asia. Some assemble in 

 vast flocks, and fly to great distances ; others take more moderate 

 flights. The plumage of all is pale isabelline yellow, of various 

 shades, and more or less variegated with deep brown. Two 

 genera only are known, one common to Africa and Asia, 

 and the other peculiar to the highlands of Central Asia. 



Gen. Pterocles, Temminck. 



Char. — Bill small, slightly arched, the sides compressed ; nostrils 

 basal, almost concealed by the frontal plumes ; wings long and 

 pointed, the first and second quills longest ; tail moderate, wedge- 

 shaped or rounded, the central feathers often lengthened ; tarsi 

 feathered in front, reticulated posteriorly ; the anterior toes bare, 

 united at their base by membrane ; hind toe minute, raised ; the 

 claws short, stout, very slightly curved. 



