Tra' che a, a tube which carries air either to the respiratory organ or to the tissues.

Trunk, the portion of the body between head and tail.

Tu' ber cle, a knob-like projection.

Ul' na, that bone of the forearm which is on the same side as the little finger.

Um' bo (pl. umbones), an elevation near the anterior end of a bivalve shell.

Un' gu lates, hoofed mammals.

U re' ter, a duct connecting the kidney with the urinary bladder.

U' ro style, a long bone forming the hinder extremity of the vertebral column of tailless amphibia.

Vac' u oles, small, clear spots in cells, filled with a watery fluid. See Food-vacuoles and Contracting vacuoles.

Valve, (1) a membranous fold which allows the blood, or other fluids, to flow in only one direction; (2) one of the two parts of the shell of a bivalve.