240 Bulletin American Museum of Natural History. [Vol. XXXVI, 



(583) Circus cinereus Vieill. 

 Circus cinereus Vieill., Nouv. Diet. d'Hist. Nat., IV, 1816, p. 454 (Paraguay). 



An immature female collected by Gonzalez at Anolaima in the Bogota 

 region measures, wing 360; tail, 228; tarsus, 72; culmen, 26 mm. The 

 under wing-coverts are marked with rusty, blackish and buffy, and the bird 

 evidently represents Circus cinereus, though I have no specimens of that 

 species (which appears not to have been before recorded from north of 

 Ecuador) in comparable plumage. 



Anolaima, 1. 



(584) Circus buffoni (Gmel.). 

 Falco buffoni Gmel., Syst. Nat., I, 1788, p. 277 (Cayenne). 



I provisionally refer to this species, which has not before been recorded 

 from Colombia, two harriers from Rio Frio which resemble one another in 

 color and differ from all descriptions, plates, and specimens of Circus buffoni 

 which I have examined, in being black below as well as above. In the color 

 of the upperparts, wings, tail and white facial markings these birds are not 

 unlike two male specimens from Buenos Aires, but the latter have the upper 

 tail-coverts white barred with grayish black, while the breast is black tinged 

 with rusty and with more or less concealed white bars or spots. The lower 

 abdomen, thighs and under tail-coverts are rusty chestnut, the two former 

 narrowly barred or tipped, the latter widely barred with white and with 

 some trace of black. The Rio Frio birds, on the other hand, have the upper 

 tail-coverts black with narrow, usually imperfect white bars, while the en- 

 tire underparts, thighs and under tail-coverts are black with a faint trace 

 of rusty on the thighs, lower abdomen and under tail-coverts, and in the 

 latter a single white spotted feather. 



Whether these birds represent a melanistic phase or undescribed form 

 of Circus buffoni the material at hand unfortunately does not show. They 

 agree approximately in size with an unsexed, apparently adult, Guiana 

 specimen which resembles Lesson's plate in being white below,^ but are con- 

 siderably smaller than the Buenos Aires birds, as is evident from the 

 appended measurements: 



1 Traits, p. 87, pi. 3, fig. 1. 



