58 



BULLETIN 117. UNITED STATES NATIONAL MUSEUM. 



white, narrowly but evenly barred with blackish. This is followed by 

 the fnlly adult plumage with white underparts, the bars, if any, 

 confined to the sides and flanks, the tail white with broken bars or 

 none, except a broad subterminal band, the back practically solid 

 ferruginous. All but the tail-characters may be obscured by partial 

 or complete melanism or ery thrism. Thus an individual which has the 

 tail of the postjuvenal plumage, is elsewhere almost wholly black, 

 while two nearly adult birds from Puno and one from Tafi del Valle 

 have the throat, breast and tibiae dark slate, the abdominal region 

 rich chestnut more or less obscured with blackish in two specimens, 

 in which the ferruginous above is also obscured with black. These 

 comments are based on a series of 24 females. Apparently similar 

 changes occur in the male, but my series of seven specimens of which 

 singidarly enough four are adult with white underparts and gray 

 back, is too small to warrant a definite statement in this respect. 



The series as a whole indicates that erythronotus is never wholly 

 gray below and if this be true it seems evident that the relationships 

 of poliosomus are with the imecilochrous-Tiyyospodius group of which 

 it may be the southern representative. 



Measurements of Buteo erythronotus. 



Place. 



Sex and age. 



Wing. Tail 



Puno, Peru 



Tafi del Valle, Province of Tucuman, Argen- 

 tina. 



Do 



Do 



Mendoza, Argentina 



Tofo, Chile 



Falkland Islands 



Puno, Peru 



Do 



Do 



Do 



Tafi del Valle, Province of Tucuman, Argonr 

 tina. 



Do. 

 Do. 

 Do. 

 Do. 



Do 



Do 



Do 



Do 



Mendoza, Argentina. . . 



Do 



Do 



Tofo, Chile 



Do 



Santa Cruz, Argentina. 



Tiena del Fuego 



Falkland Islands 



Male adult 



Male, first year. 



do 



Male, third year 



Male, adult 



do 



do 



Female, first year 



Female, third year 



Female, adult, melan.. 



do 



Female, first year 



.do. 

 .do. 

 .do. 



Female, first year, me- 

 lan. 

 Female, second year 



do : 



Female, third year. . . . . 



Female, adult 



Female, first year 



Female, second year 



do 



Female, adult 



do 



Female, second year 



Female, third year 



Female, second year, 

 melan. 



355 

 390 



362 

 363 

 365 

 363 

 363 

 402 

 418 

 397 

 404 

 388 



409 

 402 

 408 

 410 



388 

 399 

 406 

 417 

 384 

 383 

 394 

 392 

 377 

 393 

 400 

 404 



188 



228 



220 

 207 

 193 

 192 

 193 

 234 

 238 

 215 

 211 

 235 



236 

 242 

 244 

 238 



219 

 224 

 225 

 228 

 237 

 219 

 224 

 200 

 204 

 230 

 232 

 220 



