570 NORTH AMERICAN BIRDS. 



about 4.10-4.50, wing 1.85-1.95, tail 2.10-2.25. Hab. Western 

 Mexico (Mazatlan to Tehuantepec). 



P. nigriceps BAIRD. Baird's Gnatcatcher. 1 



d*. Lores, superciliary region, and greater portion of ear-coverts 

 white, in abrupt contrast with black or gray of top of head ; a 

 distinct black or gray streak behind eye, along upper edge of 

 ear-coverts ; length about 4.00-4.50, wing 1.80-1.90, tail 1.70- 

 1.85. Hab. Guatemala to Peru and Venezuela. 



P. bilineata (Bp.). White-browed Gnatcatcher. 7 

 a 1 . Exposed portion of inner web of outer tail-feather with at least the basal half 



black. 

 b l . Adult males with top of head glossy black. 



c 1 . Outer tail-feather with outer web entirely white, the inner web broadly 

 tipped with white. 



Adult male : Above light bluish gray (as in P. ccerulea), the whole 

 top of head, down to lores and auriculars, uniform glossy black ; 

 eyelids white ; lower parts white, shaded with bluish gray on 

 sides. Adult female : Top of head wholly gray, the plumage 

 otherwise as in male, but usually somewhat duller. Young : 

 Similar to adult female, but somewhat washed with brown- 

 ish the young male attaining the black by degrees, com- 

 mencing with a streak over each eye. Length about 4.25- 

 4.60, wing 1.90-2.00, tail 2.15-2.25. Eggs .54 X -42. Hab. 

 Southwestern border of United States, from southern Texas 

 to lower Colorado Valley, and thence south to Cape St. Lucas ; 

 northern Mexico. 



752. P. plumbea BAIRD. Plumbeous Gnatcatcher. 



c 2 . Outer tail-feather with outer web black, edged with white, the inner 

 web narrowly tipped with white. 



Adult male : Top of head black, as in P. plumbea, rest of upper 

 parts dark bluish gray or slate-gray ; eyelids white ; lower parts 

 dull light gray, deeper laterally, tinged with brownish poste- 

 riorly. Adult female : Similar to male, but with black on head 

 wholly replaced by the general dark gray color, the latter duller 

 than in male. Young : Similar to adult female, but more tinged 

 with brownish the young male with black of head appearing 

 gradually, as in P. plumbea. Length about 4.15-4.50, wing 1.90- 

 2.00, tail 2.15-2.25. Hab. Pacific coast of southern California 

 and northern Lower California. 



753. P. californica BREWST. Black-tailed Gnatcatcher. 

 b 1 . Adult male with top of head ash-gray, like back. 



Adult male with a curved black line bordering upper and hinder mar- 



1 Polioptila nigriceps BAIHD, Review Am. B. i. 1864, 69. 



a Culicivora bilineata BP., Consp. i. 1850, 316. Polioptila bilineata SCL., P. Z. S. 1855, 12. 



