44 Nelson North American Mainland Myiarchus. 



agree closely in this character with nigriccipillus from Costa Rica, but 

 the colors of upperparts are most like those of typical lawrencei, with 

 which I have placed them. The birds from southern Vera Cruz to 

 Guatemala occupy a belt between the ranges of querulvs on one hand 

 and plntyrhynchus on the other, and the occurrence of intergrades with 

 these forms and with nigricapilluK to the south renders the exact deter 

 mination of many specimens from this region extremely difficult. In 

 cases of this kind one is forced to name specimens arbitrarily or leave 

 them undetermined. The amount of rufous margination to inner webs 

 of tail feathers sometimes covers half the web in specimens from north 

 eastern Mexico, and in southern Vera Cruz and southward individuals 

 occur in which there is little or no trace of it, though they are not nu 

 merous. Some specimens from Jalapa and other localities farther south 

 in Vera Cruz have the buffy border on inner webs of tail feathers much 

 restricted and sometimes indistinct. The backs in winter specimens 

 throughout its range in northeastern Mexico vary from dull olivaceous 

 to olivaceous brown. Resident birds from Santa Efigenia, Oaxaca, and 

 from other points on the Pacific slope south of Tehuantepec in Chiapas 

 are more like typical lawrencei in size and color than those from the 

 southern part of its range on the. Gulf coast. 



Myiarchus lawrencei ntgricapillus (Cabanis). 



COSTA RICAN FLYCATCHER. 



1861. Myiarchus nigricapillus Cabanis, Journal fur Ornithologie, 1861, p. 

 250 (in text). 



Type locality. Costa Rica. No type nor specific locality mentioned. 



Breeding range. Central America from southern Guatemala to Costa 

 Rica. Not migratory. 



Zonal distribution. Humid Tropical. 



Subspecific characters. Crown blacker than in true lawrencei; back 

 darker olive; size smaller. 



Description of fresh plumage. Crown brownish black, sometimes tinged 

 with olive: back dark olive, slightly less grayish than in true lawrencei; 

 upper tail coverts dark broccoli brown edged with dark russet or rusty 

 rufous; wing (except first primaries) and tail feathers edged externally 

 with dark russet or rusty rufous; wing coverts bordered with cinnamon 

 or russet; chin, throat and breast dull ash gray, averaging darker than 

 in lawrencei; abdomen and under tail coverts rich sulphur yellow; inner 

 border of tail feathers usually with narrow edging of cinnamon buffy, 

 this border occasionally covering one-fourth of web. 



Measurements of specimens from Costa Rica and Nicaragua: Averages 

 of four adult males: Wing, 82 (80-83); tail, 77.2 (75-79); culmen, 16.1 

 (16-16.5); tarsus, 20.2 (20-20.5). 



Averages of four adult females: Wing, 76.5 (75-78); tail, 69.5 (66-72); 

 culmen, 16. (16); tarsus, 19.6(19-2,0). 



