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The Collaborative International Dictionary
Hydrophylliums

Hydrophyllium \Hy`dro*phyl"li*um\, n.; pl. L. Hydrophyllia, E. Hydrophylliums. [NL., fr. Gr. "y`dwr water + ? a leaf.] (Zo["o]l.) One of the flat, leaflike, protective zooids, covering other zooids of certain Siphonophora.