SIALIA. 63 
(28,021.) Similar to S. szalis, but differing in shade of blue, which is 
greenish, not purplish. Whole upper parts, with sides of head and lower 
jaw, greenish-blue ; beneath brownish-red, except abdomen to crissum, which 
are white. Female with the plumage duller, the outer web of second prima 
abruptly edged with white. 
Total length, 6.70; wing, 4.00; tail, 3.20; bill from nostril, .35; along 
gape, .80; tarsus, .80; middle toe and claw, .84. 
I was not a little surprised, on comparing a series of four Mexican 
and Guatemalan Blue Birds with about fifty from the United States, 
to find certain uniform differences in coloration and form, warranting 
the specific separation that Swainson hints at in the reference cited 
above. The shade of blue is appreciably different: instead of being 
of the rich dark purplish pure blue of S. sialis, it is of almost 
the very shade of greenish-blue seen in S. arctica, without the 
purplish lustre of the latter. The abrupt white margin of the outer 
primary in female (?) specimens I have not noticed in the North 
American bird. Of about the same length of body and wing, the 
tail is decidedly longer, measuring in the type specimen 3.20, instead 
of 2.75 or 2.80, the usual length in S. sialis. 
Although Swainson did not describe this species in such manner 
as to entitle him to it, I have preferred to adopt his name rather 
than present a new one. ap 
Smith- ‘Collee- Sex | 
sonian | tor’s | and Locality. ees Received from Collected by 
No. | No. | Age. pene 
28,021 11 ah Mirador, Mex. sare Drs, CH Sanco vis ley wee aterae as 
28,022 11 ye ue S06 RUMOUR uth) lia Gin intceiene 
Sars hla i ae a SET Su RP eas ne A 
30,661 | Ag ete Tactic, Vera Paz, Nov. i 2595" #On Salwine. 9 i 8. eters 
(Guat. 
Sialia mexicana. 
Sialia mexicana, Sw. F. B. Am. II, 1831, 202.—Scuater, P. Z. S. 1856, 
293 (Cordova) ; 1857, 126 (California) ; 1859, 362 (Xalapa).—Is. 
Catal. 1861, 11, no. 66.—Barrp, Birds N. Am. 1858, 223.—CoopEr 
& Sucxrey, P. R. R. XII, 1, 1859, 173. 
Sialia occidentalis, Towns., Aup.; Sialia cxruleocollis, Vicors. 
Figures: Aup. B. A. I, pl. 135.—Is. Orn. Biog. V, pl. 393.—Vicors, 
Zool. Beechy Voy. 1839, pl. iii. 
Hab. Western United States, from the Rocky Mountains to Pacific. Not 
noticed on the Missouri plains, British America, or Cape St. Lucas. Found 
at Xalapa and Cordova, Mex. (Sclater). 
