330 



NORTH AMERICAN BIRDS. 



cult genus, we are indebted to a receut monograph by Dr. Coues, in the 



Proceedings of the 

 Philadelphia Acad- 

 emy, for June and 

 July, 1872 (pp. 56- 

 81). With the same 

 material for our in- 

 vestigations, we have 

 been led, after a very 

 careful perusal of the 

 \alualile paper men- 

 tioned, and tedious 

 critical comparison 

 of the large material 

 at our command, to 

 adopt a somewhat 

 difficult view of the 



Mijiarchun viexicanus. 



relationship of the forms characterized, 

 their affinity as at present understood : — 



14h4^9 



The following synopsis expresses 



Common Characters. Above olivaceous, usually uniform, sometimes darker, 

 sometimes more ashy, on the head above. Head and jugulum more or less ashy, 

 though the latter is sometimes very pale. Rest of lower parts sulphur-yellow, 

 sometimes almost or quite white. Primaries, secondaries, and rectrices usually 

 more or less edged on either web with rufous ; but sometimes entirely destitute 

 of this color. 



Species and Varieties. 



A. Bill sub-conical ; sometimes nearly terete, its depth equal to, or exceeding, 

 its breadth in the middle portion ; its lateral outlines moderately divergent 

 basally ; terminal hook abrupt, strong. (^Myionax.) 



1. M. tyrannulus. No trace of rufous edgings on either wings or tail. 

 Above ashj'-olive, the pileum similar, the outer webs of wing-coverts and 

 secondaries edged with whitish. Head, laterally and beneath, ashy, the 

 throat and jugulum more whitish rest of lower parts sulphur-yellow. 

 Tail slightly rounded. 



Pileum and nape umber-brown ; upper surface umber-grayish. Bill 

 dark brown. Wing, 3..o0-3.70; tail, 3.60-3.90; culmen, .90 -.95; 

 tarsus, .80 - .90. Hab. South and Central America, from Bolivia and 

 Southern Brazil to Costa Rica ..... var. ty ranntilu.i} 



Wiole head and neck pure ash, paler on the throat, and darker on the 

 pileum ; upper surface greenish-ash. Bill black. Wing, 3.70 ; tail, 4.00 ; 

 culmen, .82 ; tarsus, .91. Hab. Ecuador and Guayaquil. 



var. p ha enc ej> li alus .' 



1 Myinrchm tyrannulus {iliJLu), Cottes. Muscicapa tyrannulus. Mull. (G. R. Gr. Hand List, 

 No. 5,527). Myiarchus t. Coues, P. A. K. S. Phila. Jul}', 1872, 71. (M. aurura, Bono. ; flavi- 

 tentris, Stevh. ; ferox, Gsi. ; suxiinsoni, Caban". ; panamcnsis, Lawr. ; voieziulensis, Lawr.) 



2 Myiarchus tyrannulus, var. plitEoceplutlus (Sclxtek). Myiarchus pkceocephalus, ScL. P. Z. S. 

 1860, 481. — Coues, P. A. N. S. 1872, 73. 



