What is "cancroidea"

Cancroidea is a superfamily of crabs, comprising the families Atelecyclidae and Cancridae, and tentatively †Montezumellidae. Four other families have been separated into new superfamilies: Cheiragonidae into Cheiragonoidea, Corystidae into Corystoidea, and both Pirimelidae and Thiidae into Portunoidea.