archelminthes

Century Dictionary and Cyclopedia

1. A hypothetical group of primitive worms, the supposed progenitors of the Acœlomi; primitive acœlomatous worms, of which a prothelmis is the conjectured parent form. They are supposed by Haeckel to have been evolved in the primordial geologic epoch in the direct line of descent of the ancestors of the human race. Their nearest living relatives are considered by him to be the Turbellaria.