Eurypterida
  板足鱟類
  Eu·ryp·te·roi·de·a n. pl.  Paleont. An extinct order of Merostomata, of which the genus Eurypterus is the type. They are found only in Paleozoic rocks. [Written also Eurypterida.]
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  Eurypterida
       n : extinct aquatic arthropods of the Paleozoic [syn: order
           Eurypterida]