iS<M I ^ IDGWAlr i Gs^ra/i/cs/ Variation in Sialia mexicana. 1^3 



as whole of sides and flanks). Total length (skin), 6.25; wing, 4.25; 

 tail, 2.60 1 ; exposed culmen, 0.40; tarsus, 0.82; middle toe, 0.58. 



The six adult males of this form before me vary remarkably 

 in coloration. The one in breeding plumage described above 

 was selected as agreeing more closely with Swainson's original 

 description than any of the others. Like Swainson's v type,' 

 this is absolutely without a trace of brown on the back or scapu- 

 lars, and the uniform blue of the upper parts is of the same rich, 

 dark purplish hue. 



An adult male in similar condition of plumage collected on 

 Mt. Orizaba, Puebla, April 19, by Mr. Nelson (No. 135,703, 

 collector's number 1040), is in general appearance similar, but 

 has a distinct patch of chestnut-brown on each side of the back 

 (on outermost anterior scapulars) , has the blue of the throat 

 and lower breast paler and duller, and the cinnamon-chestnut 

 of the breast much more extensive and absolutely unbroken in 

 the median portion. 



Another specimen from the same locality collected April 21 

 (No. 135,704) has these features still more pronounced, the 

 chestnut of the back extending quite across on the anterior 

 portion, and the whole breast, as well as the chest, being 

 uniform cinnamon-chestnut, though not quite so deep in color 

 nor so extensive as in the February specimen from Mt. Popo- 

 catapetl, mentioned below. 



An adult male in perfect plumage from Mt. Popocatapetl 

 obtained February 24, 1S93, by Mr. Nelson (No. 135,710, 

 collector's number S49), has the upper parts exactly as in the 

 example just mentioned, but the under parts are still more 

 extensively cinnamon-chestnut, this color occupying not only 

 the whole of the chest, breast, sides, and flanks, but also the 

 lower throat. The whole throat is faintly tinged with rusty, 

 and the color of the breast, etc., approaches far more closely to 

 chestnut than cinnamon. 



An example in fresh autumnal plumage from the foot-hills 

 near Charcas, San Luis Potosi (No. 124,903, November 13, 1S91, 

 P. L. Jouy) is not only wholly rich deep smalt blue above, but 



1 Average and extreme measurements of wing and tail in 4 adult females are as 

 follows : Wing : Average, 4.26 ; longest, 4.30 ; shortest, 4.22. Tail : Average, 2.64 ; 

 longest, 2.70 ; shortest, 2.55. 



