Source : Webster's Revised Unabridged Dictionary (1913)

Cladocera \Cla*doc"e*ra\, n. pl. [NL., fr. Gr. ? a sprout + ? a
   horn.] (Zo["o]l.)
   An order of the Entomostraca.

   Note: They have a bivalve shell, covering the body but not
         the head, and from four to six pairs of legs and two
         pairs of anten[ae], for use in swimming. They mostly
         inhabit fresh water.