SYLVIADiE. 



209 



[44.] 1. Erythaca (Si alia) arctica. (Swainson.) The Arctic Blue-bird. 



Genus, Erythaca. Sub-genus, Sialia, Swainson. 



Ch. Sp. Erythaca (Stalia) arctica, cyanea, subtus azurea, crisso versus albescens. 



Sp. Ch. The Arctic Blue-bird, ultramarine-blue above, greenish-blue beneath, whitish on the posterior part of 

 the belly and under tail coverts. 



Plate xxxix. 



The only specimen that we procured of this beautiful bird was shot at Fort 

 Franklin, in July, 1825. It is merely a summer visitor to the fur-countries ; and 

 we obtained no information respecting its habits. 



DESCRIPTION 

 Of a specimen killed at Great Bear Lake, lat. 64J°, July, 1825. 



Colour of the dorsal aspect ultramarine-blue ; the webs of the tertiaries and the tips and 

 inner margins of the quill and tail feathers dull umber-brown ; the base of the plumage 

 blackish-grey. Under surface. The cheeks, throat, breast, and insides of the wings greenish- 

 blue, fading, on the abdomen to greyish-blue. Vent feathers and under tail coverts white. 

 Tail beneath and insides of the quill feathers clove-brown, with a strong tinge of blue. 

 Bill and feet pitch-black. 



Form, in general, that of E. Wilsonii; but the bill is considerably narrower at the base, and 

 proportion ably longer, straighter, more faintly notched, and less bent at the tip of the upper 

 mandible : its breadth is equal to its depth. Wings three-quarters of an inch shorter than the 

 tail. The second quill feather is the longest ; the first and third are equal, and about a line 

 shorter*; the tenth is an inch and a half shorter than the second. Tail forked or deeply 

 emarginated, the central feathers being more than half an inch shorter than the exterior ones. 

 Legs and feet similarly formed with those of E. Wilsonii. 



Dimensions. 



Inches. Lines. 

 Length from the tip of the bill to the end of Length of the bill on its ridge . 



the tail ...... 7 9 ,, of the tarsus . 



„ of the tail .... 2 9 „ of the middle toe 



,, of the folded wing ... 4 4 „ of the middle nail 



„ of the bill, from the angle of the „ of the hind toe . 



mouth .0 8 „ of the hind nail 



* The relative lengths of the quill feathers are the same with those of a young specimen of E. Wilsonii, described 

 in the following page. 



2 E 



Inches. 

 . 



Lines. 



c 







10 



. 

 



7§ 

 2 



. 



4 







3 



