Thoracostraca \Tho`ra*cos"tra*ca\, n. pl. [NL. See {Thorax}, and
{Ostracoid}, a.] (Zool.)
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.
[1913 Webster]