Definition of annelida : A division of the Articulata, having
the body formed of numerous rings or annular segments, and
without jointed legs. The principal subdivisions are the
Chaetopoda, including the Oligochaeta or earthworms and
Polychaeta or marine worms; and the Hirudinea or leeches. See
Chaetopoda. - But A soon broke up into two principal stirpes, of
which one, a, became the root of the Annelida, Echinodermata,
and Arthropoda, while the other, b, gave rise to the Polyzoa and
Ascidioida, and produced the two remaining stirpes of the
Vertebrata and the Mollusca. - "Critiques and Addresses", Thomas
Henry Huxley.