AN´TI- (_in composition_). Against.
AN´TIÆ, _n. pl._ Frontal points; projections of feathers on either side
of base of culmen. (36.)
ANTIBRACH´IUM, _n._ Cubit or forearm.
A´NUS, _n._ Outlet of refuse of digestion. In birds, the same orifice
discharges the products of the genito-urinary organs.
AOR´TA, _n._ The first great artery, immediately issuing from the left
ventricle of the heart.
AOR´TIC, _a._ Pertaining to the aorta.
APERTU´RA, _n._ An opening; as, _apertura auris_, ear-opening.
A´PEX, _n._; pl. _apices_. Tip or point of anything.
APOHY´AL, _a._ A portion of the “horn” of the hyoid bone.
APONEURO´SIS, _n._ Broad, strong, fibrous membrane or band; fascia.
APOPH´YSIS, _n._ Any natural bony prominence of notable size.
APPOSED´, _a._ Mutually fitted, adapted; set over against; meeting
closely and exactly. The tomia of the bill are usually _apposed_.
APTE´RIUM, _n._; pl. _apteria_. Tract of skin where no feathers grow.
Compare PTERYLA.
AQUAT´IC, _a._ Pertaining to the water; said of birds frequenting water,
and thence drawing subsistence.
A´QUEOUS, _a._ Watery. Said of the fluid in the anterior chamber of the
eye. See VITREOUS.
AQ´UILINE, _a._ Eagle-like; belonging to the _Aquilinæ_.
ARACH´NOID, _n._ One of the three enveloping membranes of the brain,
between the _dura mater_ and the _pia mater_.
ARBOR´ICOLE, _a._ Tree-inhabiting.
ARCH´ETYPE, _n._ Original plan or idea of structure, modified or lost by
subsequent specialization.
ARCHETYP´ICAL, _a._ Having the primitive pattern or original plan of
structure.
ARC´UATE, _a._ Bow-shaped; bent regularly and gradually.
ARE´OLA, _n._; pl. _areolæ_. Small naked space on the feet between
scales.
ARE´OLAR TISSUE. The light cellular connective tissue of the body.
ARMIL´LA, _n._ Ring of color, like a bracelet, around lower end of crus.
ARM´PIT, _n._ (78.) See AXILLA.
ARTE´RIAL, _a._ Pertaining to arteries; as, arterial system, arterial
blood.
AR´TERY, _n._ Vessel conveying blood from the heart.
ARTICULA´TION, _n._ A joining together; joint.
ARTIC´ULUS, _n._ Joint of a finger or toe (commonly used to signify the
hinge itself, but better to designate any one of the segments joined by
articulation).
ARTIFI´CIAL, _a._ Elaborate; skilfully or artfully contrived. Some birds
build highly _artificial_ nests. Also, arbitrary; as, an _artificial_
classification, more or less at variance with that which a _natural_
system may be.
AR´TUS, _n._; pl. _artus_. Any member, limb.
ARYT´ENOID, _a._ Denoting certain ossicles of the larynx.
ASCAR´IDES, _n. pl._ Certain intestinal parasites.
ASH _or_ ASH´Y, _a._ Pale gray.
ASTER´NAL (_ribs_), _a._ Denoting “floating” ribs; those not joining the
sternum.
ASTRAG´ALUS, _n._ One of two proximal tarsal bones of birds, early
confluent with the tibia.
ASYMMET´RICAL, _a._ Uneven; disproportionate as to opposite, as right
and left, parts.
ASYM´METRY, _n._ Disproportion of duplicate parts or organs, or of those
which are repeated on opposite sides of a plane or axis.
AT´AVISM, _n._ Reversion, or tendency to revert, to characters of
ancestral stock.
AT´LAS, _n._ First cervical vertebra, articulating with the occipital
bone.
ATRES´IA, _n._ Closure.
AT´ROPHY, _n._ See HYPERTROPHY.
ATTEN´UATE, _a._ Growing gradually slenderer toward an extremity; or,
narrowly produced for a long distance; in neither case necessarily
sharp-pointed, which would be rather _acuminate_.
ATTYP´ICAL, _a._ Of particular character acquired in specialization from
a common type.
AUCHE´NIUM, _n._ Lower back part of neck; the scruff. (50.) (Little
used.)
AU´RAL or AURIC´ULAR, _a._ Pertaining to the ear.
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.
AVICUL´TURE, n. Care of birds.
A´VIS, _n._; pl. _aves_. Bird.