Au´ricle, n. The external ear; wanting or imperfect in birds. Also, cavity (right and left) of the heart receiving blood from the system and lungs; also called atrium.
Auric´ulars, n. pl. Peculiar feathers overlying the ear-opening.
Autoch´thonous, a. Indigenous.
Autog´enous, a. Literally, self-producing. In homology, developing from distinct and independent centres. Opposed to exogenous.
Au´topsy, n. Personal observation or examination.
Autop´tical, a. Personally inspected.
Autum´nal Plum´age. That ensuing from the first moult, if any, or prior to the spring moult, from which it is different in many birds.
A´viary, n. Place where birds are kept captive.
Avic´ula, n. Little bird; hence, nestling, fledgling, or any ungrown bird.