ARCTIC BLUE BIRD. 39 



usually returned to the fence, and warbled for a minute most delight- 

 fully. Its note, although like that of our common Sialis, is still so dif- 

 ferent as to be easily recognised. It is equally sweet and clear, but of 

 so little power (at least at this season) as to be heard only at a short 

 distance. In the spring it is louder and bolder, but is at all times 

 much less strong than that of the common species." 



Erythaca (Sialia) arctica, Siraiiison. The Akctic Blue-bird, Richards, aud 



Swains. Fauna Bor.-Amei-. vol. ii. p. 209. 

 Arctic Blue Bird, Sialia arctica, Nuttall, Manual vol. ii. p. 573. 



Adult Male. Plate CCCXCIII. Fig. 2. 



Bill of ordinary length, nearly straight, broader than high at the 

 base, compressed towards the end ; upper mandible with the dorsal line 

 straight and declinate, until near the end when it becomes convex, the 

 ridge narrow, the sides convex towards the end, the edges direct and 

 overlapping, with a distinct notch close to the narrow deflected tip ; 

 lower mandible with the angle of moderate length and narrow, the 

 dorsal line straight, the sides convex, the edges direct, the tip narrow. 

 Nostrils basal, oval. 



Head rather large ; neck short ; body moderately full. Feet of or- 

 dinary length, slender ; tarsus compressed, covered anteriorly with 

 seven long scutella, posteriorly with two very long plates meeting so 

 as to form a sharp edge ; toes of moderate length ; the first stouter, the 

 second and foiu-th nearly equal, the third much longer ; claws mode- 

 rate, well curved, slender, compressed, laterally grooved, tapering to a 

 fine point. 



Plumage soft and blended, with considerable gloss ; short bristles 

 at the base of the upper mandible. Wings very long ; the first quill 

 very small, being only seven-twelfths of an inch long, the second one- 

 twelfth shorter than the third, which is longest, but exceeds the 

 fourth only by half a twelfth, the other primaries rapidly graduated ; 

 the outer secondaries emarginate, the inner not elongated. Tail long, 

 deeply emarginate, of twelve strong feathers, of which the medial are 

 five-twelfths shorter than the lateral. 



Bill and feet black ; iris brovm. The general colour of the upper 

 parts is light azure blue, approaching to smalt blue ; the quills and 

 larger coverts dark greyish-brown, the outer tinged with blue, the pri- 



