232 



BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



173 (Upper Salinas Valley, Calif.; 1 seen Oct. 23, 1944).— Williams, Auk, 

 Ixiv, 1947, 186 (Chalk Bluffs, Weld County, Colo.; tick parasites, 1943). 



Triorchis regalis Swann, Monogr. Birds Prey, i, 1928, 427 (monogr.). 



Buteo californica Hutchins, California Mag., Mar. 1857, 393-396, fig. in text. — 

 Grinnell, Univ. California Publ. Zool., xxxviii, 1932, 267 (type loc, crit.). 



Subgenus Tachytriorchis Kaup 



Large buteonine hawks (wings usually over 400 mm.), with the 

 tail slightly less than half as long as the wing, its end square or only 

 slightly rounded; three outer primaries incised on their inner webs. 



Plumage and coloration. — Plumage full, compact, the primaries and 

 rectrices moderately rigid; general coloration white, gray, and blackish. 



Range. — Southern United States to south-central Argentina. 

 (Alonotypic.) 



BUTEO ALBICAUDATUS HYPOSPODIUS Gnrney 



Sennett's White-tailed Hawk 



Adult (sexes alike except in size). — Top and sides of head and neck 

 dark ashy gray to neutral gray, each feather more or less distinctly 

 edged with deep neutral gray; nape, scapulars, interscapulars and 

 upper back neutral gray edged with deep neutral gray, basally white; 

 lesser upper wing coverts cinnamon to mDcado brown, the scapulars 



Figure 17. — BuUo {Tachytriorchis) dbicaudatus. 



