Sipunculidan.

1854 W. B. Carpenter Princ. Compar. Physiol. (ed. 4) v. 246 The curious genus Pelonaia..in its general form and in some parts of its structure exhibits an obvious approximation to the Sipunculida.

1900 Amer. Naturalist 34 154 The collaboration of closed excretory cells and phagocytes to eliminate waste products..is found in many groups: Oligochæta, Polychæta, Hirudinea, Sipunculida, Echinoderma.

1958 Science 14 Mar. 592/1 Hemerythrin is the respiratory pigment of the phylum Sipunculida.

1973 Taxon 22 340 I would eliminate, at least provisionally, Ctenophora (to a class of Coelenterata), Gnathostomulida (to a class of Platyhelminthes),..Sipunculida and Echiurida (to classes of Annelida), [etc.].

2002 P. Herring Biol. Deep Ocean App. 284 Sipunculida (peanut worms). There are about 300 species of these unsegmented worms, most of which have bushy tentacles round the mouth.