STALIA,. 581 
back, scapulars, ete.; wings (except coverts) and tail as in 
adult; beneath white, the feathers of breast, etc., very broadly 
bordered with dark grayish or brownish; a whitish orbital 
ring. Eggs 82 xX .64. Hab. Eastern United States, north to 
Nova Scotia, Ontario, Manitoba, etc., west to base of Rocky 
Mountains; Bermudas (resident). 
766. S. sialis (Linn.). Bluebird. 
c’. Breast, etc., light ochraceous-cinnamon, the sides of neck and (usually) 
malar region similar. 
@. Above light greenish blue or cerulean-blue (much as in S. arctica), 
the sexes differing as in S. sialis; anal region cinnamon-buff; 
length 6.40-7.10, wing (male) 4.05-4.20 (4.10), tail 2.70-2.95 
(2.79), culmen .47-.50 (.49), tarsus .80-.85 (.82). Female: Wing 
3.90, tail 2.55. Hab. Highlands of Mexico, north to southern 
Arizona...... 766a. S. sialis azurea (Barrp). Azure Bluebird! 
d’. Above rich cobalt-blue, varying to ultramarine, like S. sialis; 
otherwise resembling S. azurea. Male: Wing 4.15-4.35 (4.25), 
tail 2.80-3.00 (2.93), culmen .50, tarsus .62-.65 (.63). Female: 
Wing 4.05-4.10, tail 2.70-2.80. Hab. Highlands of Guatemala 
and Honduras. 
S. sialis guatemale Ripaw. Guatemala Bluebird.? 
b?, Throat and belly blue. 
Adult male: Above rich smalt-blue (varying to ultramarine), the back 
usually with more or less of chestnut (sometimes entirely chestnut, 
rarely entirely blue*); lower parts lighter and duller blue, the breast 
and sides deep cinnamon-chestnut. (Colors duller and more suf- 
fused in winter.) Length 6.50-7.12, wing 3.95-4.45 (4.19), tail 2.62- 
3.05 (2.84), culmen .45-.50 (.48), tarsus .80-.90 (.82). Adult female: 
Head, neck, and upper parts dull gray, paler on throat, browner on 
back ; rump, upper tail-coverts, and tail bright blue, the outer web 
of lateral tail-feather whitish ; wings dull blue; breast and sides 
dull light cinnamon; belly dull grayish; wing about 4.00, tail 2.50. 
Young: Not always distinguishable with certainty from correspond- 
ing stage of S. sialis, except by slenderer bill; usually darker, how- 
ever, especially on lower parts, the throat dull grayish and sides 
tinged with dull dark brown. Eggs .81 Xx .64. Hab. Western 
United States, north to British Columbia, east to Rocky Moun- 
tains, south over table-lands of Mexico. 
(100.) 467. S. mexicana Swarns. Western Bluebird. 
1 Swainson’s Sialia azurea, usually quoted for this form, is a complete nomen nudum. The name was first 
coupled with a description by Professor Barrp (Review Am. B. i. July, 1864, 62), who is therefore to be quoted 
as its authority. 
2 §. sialie quatemale Rivew., Pr. U. S. Nat. Mus. v. June 5, 1882, 13. ; 
8 This variation is purely individual, and not at all dependent on locality, as supposed by Mr. Srrzonu 
(Cat. B. Brit. Mus. v. 1881, pp. 331-333). 
