Nelson North American Mainland Myiarchus. 39 



Zonal distribution. Lower Sonoran and Arid Tropical. 



Description of fresh plumage. Crown grayish bistre brown, a little 

 darker than back: back grayish olive brown, becoming much like 

 cinerascens in faded plumage: upper tail coverts light sepia brown, 

 strongly edged and often distinctly colored throughout with tawny olive 

 or rusty olive; primaries, secondaries, tertials and top of tail dark hair 

 brown; wing coverts and tertials edged with dull brownish white, 

 bleaching to dull whitish; primaries (except first) narrowly edged along 

 middle with rusty rufous; chin, neck and breast pale cinereous ashy, 

 little if any darker than, in winter specimens of cinerascens; abdomen 

 and under tail coverts sulphur yellow; outer web of outer tail feather in 

 some specimens uniform pale hair brown and" in others edged more or 

 less with whitish; inner web of this feather cinnamon rufous with a line 

 of dark hair brown (varying someVvhat in shade) along shaft beginning 

 on basal third of feather and gradually widening to occupy from one- 

 fourth to entire width of inner web at tip; same pattern repeated with 

 decreasing amount of dusky inward on other feathers except middle 

 pair. 



Description of first plumage ( 9 Rio Balsas, Guerrero, Mexico, June 3, 

 1903). Much like same plumage of M. cinerascens but darker; top of 

 head sepia brown with a light wash of dull tawny; back dull, dark hair 

 brown; wing coverts and tertials edged with lighter, varying from 

 pinkish buff to ochraceous buff; upper tail coverts dark cinnamon 

 rufous with dusky shaft streaks; tail cinnamon rufous with bases of 

 middle pair of feathers dusky and a narrow shaft line of same extends 

 thence toward end of feathers gradually broadening to occupy most of 

 feather near tip, but completely bordered by rufous; outer web of outer 

 feather dusky, edged broadly along middle two-thirds with pale buffy 

 whitish; outer web of other tail feathers with broad dusky band along 

 shaft and narrower edging of rufous; inner webs of all except middle 

 pair plain rufous. Underparts from chin over breast pale cinereous ashy ; 

 abdomen and under tail coverts pale yellowish white. 



Measurements. Average of ten adult males*: Wing, 91.2 (88-93); tail, 

 88.4 (85-92); culmen, 18 (17.5-21); tarsus, 22.4 (22-23). 



Averages of five adult females*: Wing, 86.8 (85-88); tail, 84.8 (81-87); 

 culmen, 17.2 (17-18): tarsus, 21.5 (21-22). 



General notes. Up to the present time, except for the brief notes 

 published with the original description, this bird has remained compara 

 tively unknown. During the spring of 1903, Mr. Goldman and I secured 

 specimens at the type locality and elsewhere throughout this region, 

 which added to specimens already in the Biological Survey and National 

 Museum form an excellent series covering a wide range in western and 

 southern Mexico. Instead of being, as the describers suggested, "a 

 small resident form of the migratory M. crinitus of eastern America, 



which being isolated in the Sierra Madre del Sur, has acquired distinc- 







*Specimens from southwestern Mexico, mainly from the region about 

 the type locality. 



