27 
DUSKY GROUS. 
TETRHO OBSCUjRUS. 
Plate XVIII. Female. 
Tetrao obscurus, Sat, in Long’s Exped. to Rocky Mount. II, p. 14. Nob. Cat. Birds 
U. S. Sp. 209, in Contr. Macl. Lyc. Phila. I, p. 23. Id. Syn. Birds U. S. Sp. 207, 
in Ann. Lyc. Nat. Hist. N. Y. pp. 127, 442. 
Philadelphia Museum , Female. 
Collection of Mr. Sabine , in London , Male and Female. 
Linne, in his genus Tetrao , brought together so great a number 
of species bearing no more than a distant resemblance to each 
other, and differing not only in their external characters, but even 
in their peculiar habits, that he might with almost the same 
propriety have included in it all typical gallinaceous birds. 
Latham very judiciously separated the genus Tinamus, as well as 
that of Perdix, which latter he restored from Brisson. Illiger 
likewise contributed to our better knowledge of these birds by 
characterizing two more natural genera, Syrrhaptes and Ortygis . 
Temminck, in his Histoire des Gallinaces, carried the number to 
seven, but has since reduced it by reuniting Coturnix to Perdix. 
The true Tetraones are divided by Vieillot into two genera, the 
Lagopodes forming a distinct one by themselves. These however 
we regard as no more than a subgenus, of which we distinguish 
three in our genus Tetrao. I. Lagopus , which represents it in 
the Arctic Polar regions; for whose climate they are admirably 
adapted by being clothed to the very nails in plumage suited to 
the temperature, furnished abundantly with thick down, upon 
which the feathers are closely applied. The colour of their 
