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n. pl.1.(Zool.) An extensive order of Hydrozoa or Acalephæ.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
(1982): Colony structure and systematic assignment of Cladochonus tenuicollis McCoy, 1847 (Hydroidea).
Hydroidea (Cnidaria: Hydrozoa) from the Cairie Bow Cay, Belize.
Observations on the settling behaviour of planulae of Clava multicornis Forskal (Hydroidea, Athecata).