34 TETEAONID^, 



Family I. TETRAONID.E. 



K^ostrils densely feathered. Tarsi and toes entirely feathered, or 

 only the tarsi feathered, or only the upper half of the tarsi feathered. 

 In the groups with naked feet the sides of the toes pectinate. 

 No spurs ever developed on the tarsi in either sex *. 



Key to the Genera t. 



A. Tarsi, feet, and toes densely covered with 



feathers . 1. Lagopus, p. 35. 



B. Tarsi entirely feathered ; toes naked, pecti- 



nate on the sides. 



a. Outer tail-featliers longer or very much 



longer than the middle pair, and curved 

 outwards in the male ; tail composed of 

 18 feathers 2. Lyruhus, p. 63. 



b. Outer tail-feathers equal to or more than 



two thirds the length of the central pair. 

 a'. No elongate tufts of feathers on each 

 side of the neck. 

 «". Outer primaries not attenuated and 

 sickle-shaped. 

 a'" . No inflatable air-sac on each side 

 of the neck in the male. 

 «*. Tail composed of 18 feathers, 



size very large 3. Tetbao, p. 59. 



6*. Tail composed of 16 feathers, 



size small 4. Caxachites, p. 68. 



b'". An inflatable au-sac on each side 

 of the neck ; tail composed of 20 



feathers 6. Dendeagapus, 



b". Outer primaries attenuated and sickle- [p. 73. 



shaped ; no inflatable air-sacs on the 

 sides of the neck ; tail composed of 



16 feathers 5. Falcipennis, p. 72. 



b'. An elongate tuft of feathers and an in- 

 flatable air-sac on each side of the 

 neck 7. Tympanuchus, 



c. Outer tail-feathers two thirds or less than [p. 77. 



two thirds the length of the central pair. 



c' . Tail very long, central feathers elongate 

 and sharp-pointed; an inflatable air- 

 sac on each side of the neck ; tad 

 composed of 20 feathers 8. Centeocehcxjs, 



d. Tail moderately long, central feathers [p. 80. 



parallel-edged and tnmcate ; no in- 

 flatable air-sac on each side of the 

 neck ; tail composed of 18 feathers . . 9. Pediocjetes, p. 82. 



* For the osteology of the American Tetraonidse see Shufeldt, Bull. U.S. 

 Geol. Surv. vi. pp. 309-350, pis. v.-xiii. (1882). 



t The generic characters are founded on the males, and are thus not always 

 applicable to the females. 



