ZONE, in anatomy, a region of the body formed by imaginary lines drawn around it transversely; used specifically of the abdominal zones or regions. In biology, a stripe or belt, as of color, on a plant, a shell, etc. Also a certain strat um of sea water, the depth of the upper and under surfaces of which are gener ally measured or calculated in fathoms. There are five zones to mark the bathy metric distribution of marine animals. Some of them are named from the dis tribution of sea plants, which also they mark: The Littoral Zone, between tide marks; the Laminarian Zone, from low water to 15 fathoms; the CaroDine Zone, from 15 to 50 fathoms; the Deep-Sea Coral Zone, 50 to 100 fathoms; the Abyssal Zone, beyond 100 fathoms.
In geography, one of the five imagin ary belts surrounding the earth. They are the North Frigid Zone, between the North Pole and the Arctic Circle; the North Temperate Zone, between the Arctic Circle and the Tropic of Cancer; the Torrid Zone, between the Tropic of Cancer and the Tropic of Capricorn; the South Temperate Zone, between the Tropic of Capricorn and the Antarctic Circle; and the South Frigid Zone, between the Antarctic Circle and the South Pole.
In geology, zones are particular beds in the stages or divisions of certain geo logical formations, as, the primordial zone. In mathematics, the portion of the surface of a sphere included between two parallel planes. Ciliary zone, in anat omy, a term for the appearance which the pigment between the ciliary pro cesses leaves on the hyaloid membrane, like the disk of a flower; also called Corona, cilia'ris. Isothermal zone, in geography and meteorology, the space between two isothermal lines.