The Collaborative International Dictionary of English v.0.48:

Myxinoidei \Myxinoidei\ prop. n.
   A suborder of hagfishes as distinguished from lampreys.

   Syn: Myxiniformes, suborder Myxiniformes, Hyperotreta,
        suborder Hyperotreta, Myxinoidea, suborder Myxinoidei.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Myxinoidei
    n 1: hagfishes as distinguished from lampreys [syn:
         Myxiniformes, suborder Myxiniformes, Hyperotreta,
         suborder Hyperotreta, Myxinoidei, Myxinoidea,
         suborder Myxinoidei]