Annelida.

Abstract

Currently as many as 14 worm phyla are recognised, which is about one half of all the animal phyla. However considering the usual requirements for preservation of fossils, it is not surprising that remains of fossil worms have seldom been found. Various kinds of burrows, tracks, castings and tubes are much more commonly encountered, but rarely provide taxonomically useful information. Because only one phylum, the Annelida, has any appreciable fossil record, it is the only worm phylum treated here. Sections deal with morphology, reproduction, classification, origin and evolution. -after Author