BIED9 OS' NORTH AKD MIDDLE AMERICA. 



679 



Idnclus] meodcanus Sclater and Salvin, Nom. Av. Neotr., 1873, 3. 



C[mchi.s\ mexicanus Coues, Key N. Am. Birds, 2d ed., 1884, 255, part (Mexico; 



Guatemala) ; 5th ed., i, 1903, 260, part.— Eidgway, Man. N. Am. Birds, 1887, 



538, part (Mexico; Guatemala). 

 [Qinclus mexicanus] var. mexicanus Baird, Brewer, and Ridqway, Hist. N. Am. 



Birds, i, 1874, 56, part. 

 ISydrobata] mexicana Gray, Hand-list, i, 1869, 267, no. 3905, part. 



CINCLUS MEXICANUS UNICOLOR (Bonaparte). 

 AMERICAN BIPPER, 



Similar to C. m. mexicanus, but paler, with color of head and neck 

 decidelly less brown; young with under parts very much paler, exten- 

 sively suffused or mottled with buffy white or very pale cinnamon- 

 buff, the chin and throat mainly (sometimes entirely) white or buffy 

 white; under wing-coy erts with much more white (mostly of this color). 



Adult male.— Length (skins), 155-192 (173); wing, 83-100 (90.9); 

 tail, 43-56 (49.1); exposed culmen, 16-19 (17.3); tarsus, 25-31 (28.8); 

 middle toe, 18-23.5 (21.3)." 



Adult female.— Length (skins), 148-182 (166.9); wing, 79-92 (89.1); 

 tail, 41-55 (46.7); exposed culmen, 16-18 (17.2); tarsus, 26-30 (27.9); 

 middle toe, 18.5-22 (19.9).* 



Mountains of western North America, from Rocky Mountains (includ- 

 ing Black Hills of South Dakota) to the Pacific coast, and from the 



« Twenty-two specimens. 

 * Twenty-five specimens. 

 Series from different geographic areas average respectively as follows: 



I have not been able to satisfy myself as to any difference in coloration, though 

 possibly those from the Pacific coast (which are smaller than those from the Eocky 

 Mountain district) are slightly darker, with the head and neck less distinctly brownish. 



