BIRDS OF NORTH AND MIDDLE AMERICA. 741 



KEY TO TITK SPECIES AND SUBSPECIES OP BASILEUTEKUS. 



a. Rump and upper tail-coverts olive-green or olive, concolor with back; tail entirely 

 dark colored. 

 5. Pileum conspicuously different in color from back; no wing-bands. (.Vdults. ) 

 c. Auricular region chestnut, like pileum. 

 d. Superciliary stripe bright yellow. {BmnleuleriiH heUi.) 

 e. Darker, especially the chestnut on sides of head; tarsus shorter (20-22 in 

 male). 

 ■/. Smaller (adult male averaging wing 57.7, tail 54.7, exposed culmen 9; 

 adult female, wing 56.5, tail 52.2, exposed culmen 9.2) ; olive-green of 

 upper parts lighter; lores mostly black. (Southeastern Mexico, in 

 States of Vera Cruz, Puebla, Mexico, and Oaxaca. ) 



Basileuterus belli belli, adults (p. 743) 



ff. Larger (adult male averaging wing 64.5, tail 61, exposed culmen 10.2; 



adult female, wing 58, tail 55.5, exposed culmen 10); olive-green of 



upper parts darker; lores mostly chestnut. ( Highlands of Guatemala 



and Chiapas) Basileuterns belli scitulus, adults (p. 744) 



ee. Lighter, especially the chestnut on sides of head; tarsus longer (23-24 in 

 male). (Southwestern Mexico, in States of Guerrero and Jalisco. 



Basileuterns belli clarus, adults (p. 745) 

 dd. Superciliary stripe white. {Ba,si,leuterus rufifroiis.) 

 e. Under parts with only the anterior half yellow, the abdomen being white; 

 sides and flanks grayish and huffy. 

 /. Back olive-green, abruptly contrasted with gray of hindneck; white of 

 posterior under parts usually more or less tinged with yellow; tail 

 relatively shorter (averaging 55.2 in male, 54.4 in female) and bill 

 larger (exposed culmen averaging 10.6). (Southeastern Jlexico, in 

 States of Vera Cruz, Puebla, Oaxaca. and Chiapas; Guatemala. ) 



Basileuterns rufifrona ruflfrons, adults (ji. 745) 



ff. Back grayish olive, scarcely different from dull gray of hindneck; white 



of posterior under parts pure, untinged with yellow; tail relatively 



longer (averaging more than 57 in male, 56 or more in female) and 



bill smaller (exposed culmen averaging less than 10). 



g. Back grayer; tail shorter (averaging less than 58 in male) ; adult male 



averaging wing 52.8, tail 57.2, exposed culmen 8.9, tarsus 20.8. 



(Eastern border of Mexican plateau, in States of Nuevo Leon, San 



Luis Potosi, and northern Vera Cruz. ) 



Basileuterns ruflfrons jouyi, adults (p. 746) 



gg. Back browner; tail longer (averaging more than 58 in male, more 



than 56 in female) ; bill smaller (exposed culmen averaging 8.9 in 



male). 



h. Tail shorter (averaging 58.8 in male, 56.2 in female) ; pileum almost 



wholly rufous. (Western and central Mexico, in States of Sina- 



loa, Jalisco, Michoacan, Guerrero, Oaxaca, Puebla, Hidalgo, and 



Guanajuato. ) 



Basileuterns ruflfrons dugesi, adults (p. 747) 

 hh. Tail longer (averaging 59.5 in male, 60.1 in female); pileum 

 brownish gray posteriorly (sometimes medially also). (North- 

 western Mexico, in States of Sonora and Chihuahua. ) 



Basileuterns ruflfrons oaudatus, adults (p. 748) 

 ee. Under parts mostly (sometimes entirely) yellow, the sides and flanks 

 olive-green. 



