Lim·u·lus n.; pl. Limuli   Zool. The only existing genus of Merostomata. It includes only a few species from the East Indies, and one (Limulus polyphemus) from the Atlantic coast of North America. Called also Molucca crab, king crab, horseshoe crab, and horsefoot.
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  horseshoe crab
       n : large marine arthropod of the Atlantic coast of North
           America having a domed carapace that is shaped like a
           horseshoe and a stiff pointed tail; a living fossil
           related to the wood louse [syn: king crab, Limulus
           polyphemus, Xiphosurus polyphemus]