The Collaborative International Dictionary of English v.0.48:

Nemathelminthes \Nem`a*thel*min"thes\, Nematelminthes
\Nem`a*tel*min"thes\, prop. n. pl. [NL. See Nemato-, and
   Helminthes.] (Zool.)
   An order of helminths, including the Nematoidea and
   Gordiacea; the roundworms. [Written also Nematelminthea.]
   [1913 Webster]