174 
COMMON BLUE-BIRD. 
Saxicola Sialis, Bonap. Syn., p. 39. . 
Erythaca (Sialis) Wilsonii, Swains, and Rich. F. Bor. Araer., vol. ii. p. 210. 
Blue-bird, Ampelis Sialis, Nutt. Man., vol. i. p. 444. 
Blue-bird, Sylvia Sialis, Aud. Orn. Biog., vol. ii. p. 84 ; vol. v. p. 452. 
Adult Male. 
Bill of ordinary length, nearly straight, broader than deep at the base, 
compressed towards the end; upper mandible with the dorsal line convex, 
the tip declinate, the edges sharp. Nostrils basal, oval. Head rather large, 
neck short, body rather full. Feet of ordinary length, slender ; tarsus 
compressed, covered anteriorly with a few long scutella, acute behind, 
scarcely longer than the middle toe ; toes scutellate above, the two lateral 
ones nearly equal ; claws arched, slender, compressed, that of the hind toe 
much larger. 
Plumage soft and blended, slightly glossed. Wings of ordinary length, 
broad, the first quill longest, the second scarcely shorter, the secondary quills 
truncato-emarginate. Tail rather long, broad, nearly even, of twelve broad, 
rounded feathers. Short bristle-pointed feathers at the base of the mandible. 
Bill and feet black, the soles yellow, iris yellowish-brown. The general 
colour of the upper parts is bright azure-blue, that of the lower yellowish- 
brown, the belly white. Shafts of the quills and tail-feathers dusky. 
Length 7 inches, extent of wing 10 ; bill along the ridge £, along the edge 
§ ; tarsus 
Adult Female. 
The female has the upper part of a tint approaching to leaden, the 
fore-neck and sides yellowish-brown, but duller than in the male, the belly 
white. 
Length 63 inches. 
Young Bird. 
When fully fledged, the young have the upper part of the head, the back 
of the neck, and a portion of the back broccoli-brown ; the rest of the upper 
part much as in the female. The lower parts are light grey, the feathers of 
the breast and sides margined with brown. 
In a male preserved in spirits, the roof of the mouth is flat, and similar 
to that of the Thrushes ; the tongue triangular, deeply emarginate and 
papillate at the base, very thin, flat above, horny towards the end, tapering 
to a slit point, and having the edges lacerated. The oesophagus, a b c, is 2\ 
inches long, its width at the upper part 4 twelfths; the proventriculus, b 
c, large. The stomach, d e, is of moderate size, broadly elliptical, a little 
compressed, 8 twelfths long, 7 twelfths broad ; its muscles distinct, the 
lateral of considerable thickness, the lower very thin, the tendons elliptical; 
the epithelium tough, dense, with longitudinal rug®. The intestine, efg h 
