TETRAO, in ornithology; a genus of birds belonging to the order of gallinae, and is thus characterized by Linnaeus: There is a spot near the eyes naked or papillose, or covered, though more rarely, with feathers. Gmelin has enumerated about 65 species. The genus tetrao comprehended both the grouse, partridge, and quail; but Dr Latham, with great judgment and propriety, has made two genera of them, under the names of tetrao, comprehending the grouse; and perdix, comprehending the partridge and quail. Dr Latham thus distinguishes the genus tetrao: The bill is like a crooked cone, with a naked scarlet skin above each eye, and the feet feathered to the toes. The perdix he characterizes by a bill convex, strong, and short; the nostrils are covered above with a callous prominent rim; the orbits are papillose; the feet naked, and most of the species are furnished with spurs. He reckons 20 species under the tetrao, and 48 under the perdix. As we highly approve of this new arrangement of Dr Latham, we are disposed to follow it; but as a reference has been made from PERDIX to this place, it is proper that we should also give some account of that genus.