SIALIA, 



63 



(28,021.) Similar to S. sialis, but differing in shade of blue, wliich 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 primary 

 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 w^hite 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. 



Locality. 



Mirador, Mex. 



Tactic, Vera Paz, 

 [Guat. 



When 

 Collected. 



Nov. 5, '59. 



Keceived from Collected hj 



Dr. C. Sartorius. 

 0. Salvin. 



Sialia mexicana. 



Sialia mexicana, Sw. F. B. Am. II, 1831, 202.— Sclater, P. Z. S. 18.56, 



293 (Cordova) ; 1857, 126 (California) ; 1859, 362 (Xalapa).— Ib. 



Catal. 1861, 11, no. 66.— Baikd, Birds N. Am. 1858, 223.— Cgopee 



& SucKLEY, p. R. R. XII, II, 1859, 173. 

 Sialia occidentalis, Towns., Aud. ; Sialia casriileocollis, Vigors. 

 Figures : Aud. B. A. II, pi. 135.— Ib. Orn. Biog. V, pi. 393.— Vigors, 



Zool. Beechy Voy. 1839, pi. iii. 



Hah. 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). 



