2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



Description of type. — All feathered parts of top of head black, 

 the feathers of the crown and the occipital crest with their basal half 

 or more pure white, much of this color usually showing through 

 among the overlapping feathers ; scapulars, interscapulars, back, upper 

 wing coverts black ; remiges externally fuscous black to black, crossed 

 by five or six dull fuscous bars about equally spaced, the bars being 

 slightly narrower than the black interspaces and becoming mottled 

 or edged with whitish on the inner margin of the inner webs, these 

 bars grayish white on the under surface of the remiges ; rump black, 

 the upper tail coverts black, each feather crossed by two or three nar- 

 row white bars which are slightly mottled with brownish gray, and 

 also narrowly tipped with white; rectrices black paling to whitish 

 basally and crossed by four broad bands of deep ashy gray mottled 

 with pale fuscous and whitish, and narrowly tipped with whitish; 

 all the tail bands white on the under surface ; chin black, the feathers 

 white basally; feathered portions of lower cheeks and auriculars, 

 throat, breast, sides, and upper abdomen black; lower abdomen and 

 flanks black spotted sparingly with narrow, semitransverse white 

 flecks ; thighs black broadly barred with white, the black interspaces 

 somewhat broader than the white bars (in typical tyrannus these 

 white bars are very narrow lines) ; under tail coverts like the thighs 

 and flanks but with the white bars still broader and more broadly 

 spaced; under wing coverts mostly white broadly barred with black, 

 the outer, greater, under primary coverts white with only a sub- 

 terminal and a subbasal black bar (in typical tyrannus the under wing 

 coverts are black with sparse and narrow white barrings). 



Young birds of both races tend to have more white on the under 

 wing coverts and tibiae than do the adults, but even here the difference 

 between comparable birds of the two subspecies is striking. 



Measurements of type. — Wing 381 ; tail 309.8; culmen from cere 

 27.5 ; tarsus 81 ; middle toe without claw 44 mm. 



In size 6". t. serus averages smaller than 6". t. tyrannus; thus males 

 of serus have wing lengths of 354-394 (379-5 mm.) and tails 291. i- 

 325 (309.8) in length as opposed to wing lengths of 362-422 (398.3 

 mm.) and tail lengths of 365-367 (366 mm.) in the nominate race; 

 females of serus have wing lengths of 353-444.5 (412.5 mm.) and 

 tail lengths of 289-386 (337 mm.), while females of tyrannus 

 have wings of 428-460 (443.7 mm.) and tails measuring 370-405 

 (388.8 mm.) 



Range. — Resident in heavily forested areas of the tropical zone 

 from southern Mexico (Oaxaca, Chiapas, San Luis Potosi, Puebla, 

 Veracruz, Campeche, and Yucatan) south through Guatemala, Hon- 



