580 



BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



EMPIDONAX DIFFICILIS CINERITIUS (Brewster). 

 SAN LUCAS FLYCATCHER. 



Similar to E. d. difficilis, but color of upper parts averaging duller 

 and grayer, under parts paler, and bill usually narrower. 



Adult maZe.— Length (skins), 115-127 (12iB); wing, 607-706 (5:). 

 tail, 54.5-60.5 (57.5); exposed eulmen, 11.5-13.5 (12.3); \\ddth of bill 

 at nostrils, 5-5.5 (5.1); tarsus, 16-17.5 (16.6); middle toe, 8-9.5(8.6).« 



Adult female.— Length (skins), 113-128 (120); wing, 58-65 (61.7); 

 tail, 53-60 (55.1); exposed eulmen, 11-12.5 (11.6); width of bill at 

 nostrils, 5-5.5 (5.2); tarsus, 15.5-17 (16.3); middle toe, 8-9 (8.2).^ 



Lower California (Sierra Laguna; Cape San Lucas; San Jose del 

 Rancho; La Paz; Comondu; San Fernando; San Telmo; Los Elisos; 

 Santa Rosalia Bay; San Benito and Santa Margarita islands; Han- 

 son Laguna; La Grulla; Rancho San Tomas; Yallecito; San Pedro 

 Martir Mountains) and adjacent portion of San Diego County, Cali- 

 fornia (Cuymaca Mountains, breeding between 4,000 and 6,000 feet). 



Empidonax flaviventris (not of Baird) Cooper, Orn. Cal., 1870, 329, part (Cape 



San Lucas). — Coues, Check List, 1873, no. 259, part. 

 [Empidonax] flaviventris Coues, Key N. Am. Birds, 1872, 175, 176, part. 

 Empidonax difficilis (not of Baird) Ridgway, Norn. N. Am. Birds, 1881, no. 323, 



part.— Belding, Proc. U. S. Nat. Mus., vi, 1883, 348 (Victoria Mts., Lower 



California). — American Ornithologists' LTnion, Check List, 1886, no. 464, 



part. 

 Evipidonax flaviventris difficilis Coues, Check List, 2d ed., 1882, no. 389, part. 



« Twenty specimens. 

 b Ten specimens. 



I have considerable difficulty in separating this form*satisfactorily from E. d. difficilis, 

 from which it certainly is not more than subspecifically distinct, birds from the 

 extreme northern portion of Lower California and some of those from San Diego County, 

 California, being unmistakable intergrades, as are also some of those from Arizona and 

 Sonora. In fact, beyond the duller and grayer or less olive coloration of upper parts 

 and less pronounced yellowness of the under surface, comparing specimens in corre- 

 sponding condition of plumage, I can find no differences that are constant or reasonably 

 characteristic. The differences appear to be more pronounced in the young (first 

 plumage) than in adults, those of E. d. cineritius being lighter and much less olive 

 (more buffy grayish brown) above and decidedly paler (dull white or buffy white — not 

 distinctly yellowish) beneath. 



