Source : Webster's Revised Unabridged Dictionary (1913)

Entomostraca \En`to*mos"tra*ca\, n. pl. [NL., fr. Gr. ? cut in
   pieces + ? burnt clay, the hard shell of Testacea.]
   (Zo["o]l.)
   One of the subclasses of Crustacea, including a large number
   of species, many of them minute. The group embraces several
   orders; as the Phyllopoda, Ostracoda, Copepoda, and
   Pectostraca. See {Copepoda}, {Phyllopoda}, and {Cladocera}.

Source : WordNet®

Entomostraca
     n : in some older classifications includes the Branchiopoda and
         Copepoda and Ostracoda and Cirripedia; no longer in
         technical use [syn: {subclass Entomostraca}]