Tho`ra*cos"tra*ca\, n. pl. [NL. See Thorax
, and Ostracoid
, a.] (Zo["o]l.) An extensive division of Crustacea, having a dorsal shield or carapec? ??niting all, or nearly all, of the thoracic somites to the head. It includes the crabs, lobsters, shrimps, and similar species.