Source : Webster's Revised Unabridged Dictionary (1913)

Volvox \Vol"vox\, n. (Bot.)
   A genus of minute, pale-green, globular, organisms, about one
   fiftieth of an inch in diameter, found rolling through water,
   the motion being produced by minute colorless cilia. It has
   been considered as belonging to the flagellate Infusoria, but
   is now referred to the vegetable kingdom, and each globule is
   considered a colony of many individuals. The commonest
   species is Volvox globator, often called globe animalcule.

Animalcule \An`i*mal"cule\, n. [As if fr. a L. animalculum, dim.
   of animal.]
   1. A small animal, as a fly, spider, etc. [Obs.] --Ray.

   2. (Zo["o]l.) An animal, invisible, or nearly so, to the
      naked eye. See {Infusoria}.

   Note: Many of the so-called animalcules have been shown to be
         plants, having locomotive powers something like those
         of animals. Among these are {Volvox}, the
         {Desmidiac[ae]}, and the siliceous {Diatomace[ae]}.

   {Spermatic animalcules}. See {Spermatozoa}.

Source : WordNet®

Volvox
     n : type genus of the Volvocaceae; minute pale green flagellates
         occurring in tiny spherical colonies; minute flagella
         rotate the colony about an axis [syn: {genus Volvox}]