What is "anomura"

Anomura \An`o*mu"ra\, ||Anomoura \An`o*mou"ra\, n. pl. [NL., fr. Gr. ? lawless + o'yra` tail.] (Zo["o]l.) A group of decapod Crustacea, of which the hermit crab in an example.

Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans includes the word crab, all true crabs are in the sister group to the Anomura, the Brachyura (the two groups together form the clade Meiura).