Merostomata \Mer`o*stom"a*ta\, n. pl. [NL., fr. Gr. ? thigh + ?, -?, mouth.]

(Zo["o]l.) A class of Arthropoda, allied to the Crustacea. It includes the trilobites, Eurypteroidea, and Limuloidea. All are extinct except the horseshoe crabs of the last group. See Limulus.

Source: Webster's Revised Unabridged Dictionary (1913)