I Co RlDGWAY, (Geographical Variation in Sialia mexicaua. I April 



smalt) ; female with cinnamomeous color of under parts paler and much 

 less extensive. 1 



a. Typical form (true 5. m. occiden/alis). 



Adult male in spring (type, No. 1930, Columbia River; J. K. Town- 

 send) : Upper parts rich cobalt blue; sides of upper back (not scapulars) 

 chestnut, forming two somewhat wedge-shaped patches, nearly connected 

 anteriorly, the median feathers of the upper back being tipped with 

 chestnut; tips of remiges (broadly) brownish dusky. Sides of head and 

 neck, chin, throat, and chest cobalt-blue, rather lighter than upper parts; 

 sides of breast wholly chestnut, this color extending across the upper 

 breast and posteriorly over the sides to the flanks, where considerably 

 paler; median lower breast or upper belly light grayish blue, fading into 

 dull white on lower belly and anal region; under tail-coverts pale grayish 

 blue margined with grayish white, and with dusky shafts. Bill deep 

 black; legs and feet dark brown. Total length (skin), 6.10; wing, 4.10; 

 tail, 2.55; exposed culmen (tip of bill broken) ; tarsus, 0.80; middle toe, 

 0.60. 



Adult male in autumn (No. 107,287, Humboldt Bay, California, Nov. 

 21, 1SS5; Chas. H. Townsend) : Similar to the male in spring, as 

 described above, but feathers of hinder half of head, neck, back, chin, 

 throat, and chest indistinctly tipped with pale brownish gray, considerably 

 obscuring the blue, which on the chin, throat, and chest is considerably 

 paler than on the upper parts; feathers of chestnut patch on breast tipped 

 with paler; remiges and rectrices with narrow terminal margins of whitish. 

 The blue is of a much more purplish hue than in the type, and the chest- 

 nut color on the sides of the back is more restricted, but these are indi- 

 vidual, not seasonal, differences. Total length (skin), 6.00; wing, 4.05; 

 tail, 2.48; exposed culmen, 0.43; tarsus, 0.75; middle toe, 0.55. 



Adult female in spring (No. 82,590, Marin Co., California, April 15, 

 1S7S: C. A. Allen): Top of head and hind-neck mouse-gray, faintly 

 tinged with light blue, especially on hind-neck; back and scapulars hair- 

 brown, becoming paler and grayer, and tinged with light blue, posteriorly ; 

 rump, upper tail-coverts, lesser wing-coverts, and tail cerulean blue, 

 brightest on rump; outer web of lateral tail-feather broadly edged with 

 white; middle wing-coverts dusky, margined with grayish blue; greater 

 coverts and tertials deep grayish brown margined with light brownish 

 gray; primary-coverts similar, but strongly tinged with blue; outer webs 

 of primaries light glaucous-blue, narrowly edged with whitish, the outer- 

 most one broadly and sharply edged with pure white. Sides of head 

 grayish brown, more decidedly brown on ear-coverts, the eyes encircled 



1 Average and extreme measurements of wing and tail in a series of 82 adult males 

 (including both true occidentalis and bairdi) areas follows: Wing: Average, 4.20; 

 longest, 4.55 ; shortest, 3.90. Tail : Average, 2.63 ; longest, 2.80 ; shortest, 2.40. 



