sand crab

from The Century Dictionary.

• noun A crab of the genus Ocypoda, which lives on sandy beaches, runs very swiftly, and burrows in the sand; also, the lady-crab, Platyonychus ocellatus. See cut under Platyonychus.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a crab of the Hippoidea superfamily of decapod crustaceans