lady-crab

from The Century Dictionary.

• noun The commonest edible crab of the United States, Callinectes hastatus, upon the carapace of which is traceable an outline like that of a woman's bust: extended to various other swimming-and sand-crabs, as Platyonychus ocellatus. See cut under Platyonychus.
• noun See crab, 1.
• noun In the Channel Islands, Portunus puber.