Thoracostraca

Tho`ra`cos´tra`ca


n. pl.1.(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.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.