Merostomata
A taxonomic class of aquatic chelicerate arthropods, including extinct sea scorpions (Eurypterida) and extant horseshoe crabs (Xiphosura). Used in biological and paleontological contexts.
Merostomata includes horseshoe crabs and sea scorpions.
From 腿 (thigh) + 口 (mouth) + 類 (group), likely a calque of the scientific name Merostomata (from Greek mēros 'thigh' + stoma 'mouth'), referring to the leg-like appendages near the mouth.