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The class Echinodermata which includes the sea urchins. They have a calcareous, usually more or less spheroidal or disk-shaped, composed of many united plates, and covered with movable spines. See Spatangoid, Clypeastroid. [Written also Echinidea, and Echinoida.]

The Echinodermata.

A genus of echinoderms, including the common edible sea urchin of Europe.

o eclipses. Lunar ecliptic limit (Astron.), the space of 12º on the moon's orbit from the node, within which, if the moon happens to be at full, it will be eclipsed. -- Solar ecliptic limit, the space of 17º from the lunar node, within which, if a conjunction of the sun and moon occur, the sun will be eclipsed.…

magnets. (f) Positive electricity, the electricity that appears at the positive pole or anode of a battery, or that is produced by friction of glass; -- called also vitreous electricity.

Without a node. Gray.

A process by which certain coral polyps, echinoderms, annelids, etc., spontaneously subdivide, each individual thus forming two or more new ones. See Strobilation.

A node, or gland in the lymphatic system; as, a lymphatic ganglion.

One of the classes of echinoderms.

In echinoderms, one of the areas or zones intervening between two ambulacra. See Illust. of Ambulacrum.

At the same node with opposite or whorled leaves, but occupying a position between their places of attachment.

Of or pertaining to internodes; intervening between nodes or joints.

standing alone; detached; separated from others. Isolated point of a curve. (Geom.) See Acnode.

admit of motion; an articulation, whether movable or not; a hinge; as, the knee joint; a node or joint of a stem; a ball and socket joint. See Articulation. A scaly gauntlet now, with joints of steel, Must glove this hand. Shak. To tear thee joint by joint. Milton.

Having joints; articulated; full of nodes; knotty; as, a jointed doll; jointed structure. "The jointed herbage." J. Philips. -- Joint"ed*ly, adv.

See Node.

The portion of a vibrating string, air column, etc., between two nodes; -- called also ventral segment. Loop knot, a single knot tied in a doubled cord, etc. so as to leave a loop beyond the knot. See Illust. of Knot.

r pertaining to, the genus Madrepora. Madreporic plate (Zoöl.), a perforated plate in echinoderms, through which water is admitted to the ambulacral tubes; -- called also madreporic tubercule.

The madreporic plate of echinoderms.

Same as Internode.