Air-sacs.–Membranous receptacles, filled with air, in communication with the respiratory organs or passages. Pouches are often exaggerated air-sacs.
Alar bar.–A coloured bar across the wing (ala).
Allantois.–A vascular sack, growing from the hind-gut of the embryo and enclosed by the amnion; the two fuse together and form the Chorion, which lines the egg-shell, and takes upon itself respiratory functions.
Altrices or Nidicolae.–Nestlings which, being hatched in a helpless condition, are fed by their parents or inhabit the nest for a considerable time.
Amnion.–A membrane which grows in the developing egg from the ends and sides of the embryonic area, and encloses the embryo at an early period.
Bronchi (p. [13]).
Bronchial syrinx.–One in which outer tympaniform membranes exist between two or more successive bronchial semi-rings, while an inner tympaniform membrane may also be present. In typical cases the trachea has no sounding membranes.
Chest.–The same as the upper breast or base of fore-neck.
Chorion.–See Allantois.
Compressed.–Used of lateral compression as opposed to vertical (depressed).