hydrophyllium

Century Dictionary and Cyclopedia

1. n. The peculiar protective envelop or hydrotheca of the hydranths of some oceanic hydrozoans, as the Siphonophora, of laminar or foliaceous character. Also called bract.

GNU Webster's 1913

1. n. One of the flat, leaflike, protective zooids, covering other zooids of certain Siphonophora.