The Collaborative International Dictionary of English v.0.48:

Hyperotreta \Hy`per*o*tre"ta\
   (h[imac]`p[~e]r*[-o]*tr[=e]"t[.a]), n. pl. [NL., fr. Gr.
   "yperw`,n the palate + trhto`s perforated.] (Zool.)
   An order of marsipobranchs, including the Myxine or hagfish
   and the genus Bdellostoma. They have barbels around the
   mouth, one tooth on the palate, and a communication between
   the nasal aperture and the throat. See Hagfish. [Written
   also Hyperotreti.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

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