The Collaborative International Dictionary of English v.0.48:

Rhizopoda \Rhi*zop"o*da\, n. pl. [NL., fr. Gr. ??? a root +
   -poda.] (Zool.)
   An extensive class of Protozoa, including those which have
   pseudopodia, by means of which they move about and take their
   food. The principal groups are Lobosa (or Am[oe]bea),
   Helizoa, Radiolaria, and Foraminifera (or Reticularia). See
   Protozoa.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Molluscoidea, including Brachiopoda and Bryozoa. Mollusca,
including Cephalopoda, Gastropoda, Pteropoda, Scaphopoda,
Lamellibranchiata or Acephala. Echinodermata, including
Holothurioidea, Echinoidea, Asterioidea, Ophiuroidea, and
Crinoidea. C[oe]lenterata, including Anthozoa or Polyps,
Ctenophora, and Hydrozoa or Acalephs. Spongiozoa or
Porifera, including the sponges.
Protozoa, including Infusoria and Rhizopoda. For
definitions, see these names in the Vocabulary.
[1913 Webster] Animalcular

WordNet (r) 3.0 (2006):

Rhizopoda
    n 1: creeping protozoans: amoebas and foraminifers [syn:
         Rhizopoda, subclass Rhizopoda]