TYRANNID^ — THE FLYCATCHERS. 333 



decidedly darker (except in var. lawrencei); throat and jugulum ashy-white ; 

 rest of lo\yer parts sulphur-yellow. Hab. Central and South America, and 

 Jamaica. 



Pileum sooty-brown, decidedly darker than the back ; wings and tail 

 entirely destitute of rufous edgings, except a faint tinge on outer webs 

 of inner secondaries and rectrices, towards the base. Tail faintly 

 rounded. Wing, 3.00; tail, 3.10; cnlmen, .80; tarsus, .65. Hab. 

 Jamaica var. tristis} 



Pileum grayish-brown, not appreciably darker than the back; outer 

 webs of inner secondaries and primaries and rectrices faintly edged 

 with rufous. Wing, 2.80-3.40; tail, 2.85-3.45; culmen, .85 -.90; 

 tarsus, .75 -.80. Hab. Northern Mexico, from northern boundary, 

 south to Colima, Tehuantepec, Yucatan, and Salvador . var. lawrencei.- 



Pileum sooty-blackish, decidedly and abruptly darker than the back. 

 Outer webs of wing-coverts, primaries, secondaries, and rectrices dis- 

 tinctly edged with rufous. Yellow beneath brighter than in lawrencei. 

 Wing, 3.20-3.30; tail, 3.15 -3.30; culmen, .80-.85; tarsus, .75 -.80. 

 Hab. Central America from Panama to Guatemala (grading into var. 

 Zau;reMcei in Tehuantepec, and Orizaba) . . . var. nigricapillus .^ 



Pileum deep black, abruptly different from the greenish-olive of the 

 back, and separated from it by a more ashy shade. Wings and tail 

 wholly destitute of rufous edgings. Yellow beneath brighter than in 

 var. 'm'gricapillus. Wing, 3.20; tail, 3.20; culmen, .85; tarsus, .78. 

 Tail about even. Hab. Northwest South America, from Ecuador 

 northward (grading into nigricapillus on Isthmus of Panama). 



var. nigriceps.* 



^ Myiarchus tristis (Gosse), Coues. Myiobius tristis, Gosse, B. Jam. 1 67, pi. xli. Myiarchus t. 

 CouES, p. A. N. S. July, 1872, 80. 



^ Myiarchus tristis, var. lawrencei (Giraud), Baird. Tyrannula lawrencei, Giraud, 16 sp. 

 Tex. B. pi. ii. Myiarchus I. Baird, Birds N. Am. 1858, 181, pi. xlvii, f. 3. — Coues, P. A. N. S. 

 July, 1872, 74. 



Ohs. — The most typical specimens are from Mazatlan and northward, across the northern 

 portion of Mexico. On the eastern coast, specimens from Mirador and Orizaba already strongly 

 incline toward var. nigricapillus. 



^ Myiarchus tristis, var. nigricapillus, Cabaxis. ^'■Myiarchus nigricajnllus, Caban." Scl. 

 Cat. Am. B. 1862, 233, et Auct. M. lawrencei, Coues, P. A. N. S. 1872, 74 (in part). ■ 



Ohs. — A very strongly differentiated form, but unquestionably grading into var. lawrencei on 

 the one hand, and var. nigriceps on the other. 



* Myiarchus tristis, var. nigriceps, Sclateu. Myiarchus nigriceps, Scl. P. Z. S. 1860, 68, 

 295. —Coues, P. A. N. S., July, 1872, 75. 



Obs. • — The last three races appear to he all reducible to one species, as, taking the large series 

 of specimens before us (over 30 skins), we find it impossible to draw the line between them. 

 Specimens from Southern Mexico are referrible, with equal propriety, to lawrencei or to nigrica- 

 pillus, while skins from Panama of 7iigriccps are less typical than those from Ecuador. This 

 case of gradually increasing melanistic tendency as we proceed southward affords an exact parallel 

 to that of Vireosylvia gilvus and V. josephx, Sayornis nigricans and S. aquaticus, and. many 

 other cases. 



