The Collaborative International Dictionary of English v.0.48:

Myxophyta \Myx*oph"y*ta\, n. pl. [NL.; Gr. ? mucus, slime + ?
   plant.] (Bot.)
   A phylum of the vegetable kingdom consisting of the class
   Myxomycetes. By some botanists it is not separated from the
   Thallophyta.
   [1913 Webster]