||Crus*ta"ce*a (kr?s-t?"sh?-?), n.
pl. [Neut. pl. of NL. crustaceus pert. to the
crust or shell, from L. crusta the hard surfsce of a body,
rind, shell.] (Zoöl.) One of the classes of the
arthropods, including lobsters and crabs; -- so called from the
crustlike shell with which they are covered.
&fist; The body usually consists of an anterior part, made up
of the head and thorax combined, called the cephalothorax,
and of a posterior jointed part called the abdomen,
postabdomen, and (improperly) tail. They breathe by
means of gills variously attached to some of the limbs or to the
sides the body, according to the group. They are divisible into
two subclasses, Entomostraca and Malacostraca, each of which
includes several orders.
