\Ve*lel"la\, n. [NL., dim. from L. velum a veil, a
sail.] (Zo["o]l.)
Any species of oceanic Siphonophora belonging to the genus
{Velella}.
Note: These creatures are brilliantly colored and float at
      the surface of the sea. They have an oblong, disklike
      body, supported by a thin chitinous plate, from which
      rises a thin diagonal crest which acts as a sail. The
      feeding and reproductive zooids hang down from the
      under side of the disk.