Ech`i*noi"de*a (?), n. pl. [NL. See Echinus, and -oid.] Zool.

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.]


© Webster 1913.

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