[44.] 1. E rythaca (Sialia) arctica. (Swainson.) The Arctic Blue-bird.
Gen jjs , Erythaca. Sub-genus, Sialia, Swainson .
Ch . Sp . Erythaca (Sia l ia ) a rc t ic a , cyanea, subtus azurea, crisso versus albescens.
Sp . Ch . T h e A r c t ic B l u e -b ir d , ultramarine-blue above, greenish-blue beneath, whitish on the posterior part of
the belly and under tail coverts.
P late x xx ix.
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. 64 J?, July, 1825.
C olour 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.
F orm, in general, that of E. Wilsonii ; but the bill is considerably narrower at the base, and
proportionably 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.
D im en sio n s.
Length from the tip of the bill to the end ofInches. Lines. Length of the bill on its ridge . .I nches. 0
Lines
6 . the tail . . . , . 7 9 „ of the tarsus . 0 10 ,, of the tail . . . -2 9 „ of the middle toe . 0 7£ „ of the folded wing . . -. 4 4 ■ of the middle nail . 0 ,, of the bill, from the angle of the ,, of the hind toe . . 0 4 mouth . . . . 0 8 „ of the hind nail 0 3
* The relative lengths of the quill feathers are the same with those of a young specimen of E. Wilsonii, described
in the following page.