20 PROCEEDINGS OF THE IfATIONAL MUSEUM vol. 74 



RenmiJcs. — Basileutems as a group is clearly of South American 

 origin, but now has a wide range, both latitudinally and altitndinally. 

 As here restricted it ranges from Uruguay and Argentina north- 

 ward througli Central America to tropical Mexico, but avoids the 

 great Amazonian forest region, only one species invading its east- 

 ern edge. Of the 32 species herein recognized 13 belong to the 

 Tropical and 15 to the Subtropical Zone, while only 4 are found in 

 tlie Temperate Zone. With a few exceptions the derivation of these 

 Subtropical Zone forms is obscure; they are in the main not zonal 

 representatives, but rather distinct or even isolated species, although 

 a number of them have become split up into geographical races. 



The three-striped pileum, which is found in so many species of 

 this group, is a feature found also in other genera of this family 

 [HehnitJieros, Seiwms)^ and is probably without especial significance 

 as indicative of affinity. Aside from the genera treated in the 

 present paper, Basileutems probably finds its nearest relative in 

 Myiohorus. 



KEV TO THE SPECIES OF BASILEUTERUS 



A.^ I'ileuin dull or dark gray, without a differently colored coronal .stripe or 

 spot. 

 b.^ Under parts whitish or buffy. 



c* Superciliaries and cheeks more or less buffy. 

 d.' Pileum with no definite dark lateral stripe. 



e.' Superciliaries and cheeks bright buffj- (ciunamon buff). 



Basileuterus mesoleucus. 

 e.'' Superciliaries and cheeks pale buffy (pinkish buff). 



Basileuterus bolivianus. 

 d." Pileum with a definite dark lateral stripe. 



Basileuterus rivularis. 

 c." Superciliaries and cheeks Avhitish or grayish, 

 d.' Pileum uniform gray ; superciliaries white. 



Basileuterus leucophrys. 

 d." Pileum gray medially, black laterally : superciliaries gray. 



Basileuterus leucoblepharides. 



b.'' Under parts yellow Basileuterus griseiceps. 



A.' Pileum not gray or rufous, or if gray then with a conspicuous coronal spot 

 or stripe of a different color. 



b.' Broad superciliaries and sides of the head in general slaty gray. 



c' Abdomen white Basileuterus castaneiceps. 



c.^ Abdomen yellow, 

 d.' Throat grayish. 



e.' Coronal spot brownish orange Basileuterus coronatus. 



e." Coronal spot bright yellow. 



f.^ Breast grayish like the throat. 



Basileuterus cinereicollis. 

 f." Breast yellow like the abdomen. 



Basileuterus conspicillatus. 

 d.' Throat yellow like the rest of the under parts. 



Basileuterus fraseri. 



