Part 133

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.