Source : Webster's Revised Unabridged Dictionary (1913)

Nectocalyx \Nec`to*ca"lyx\, n.; pl. {Nectocalyces}. [NL., fr.
   gr. ? swimming + ? a calyx.] (Zo["o]l.)
   (a) The swimming bell or umbrella of a jellyfish of medusa.
   (b) One of the zooids of certain Siphonophora, having
       somewhat the form, and the essential structure, of the
       bell of a jellyfish, and acting as a swimming organ.