The Collaborative International Dictionary of English v.0.48:

Hirudinea \Hir`u*din"e*a\, n. pl. [NL., fr. L. hirudo,
   hirudinis, a leech.] (Zool.)
   An order of Annelida, including the leeches; -- called also
   Hirudinei.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Annelida \An*nel"i*da\, n. pl. [NL. See Annelid.] (Zool.)
   A division of the Articulata, having the body formed of
   numerous rings or annular segments, and without jointed legs.
   The principal subdivisions are the Ch[ae]topoda, including
   the Oligoch[ae]ta or earthworms and Polych[ae]ta or
   marine worms; and the Hirudinea or leeches. See
   Ch[ae]topoda.
   [1913 Webster]