(Zool.) The order of Crustacea which includes the shrimps, lobsters, crabs, etc. Note: They have a carapace, covering and uniting the somites of the head and thorax and inclosing a gill chamber on each side, and usually have five (rarely six) pairs of legs. They are divided into two principal groups: Brachyura and Macrura. Some writers recognize a third (Anomura) intermediate between the others.
