This book is designed to bring together everything known about the Sipuncula, a phylum of marine worms. It can be viewed as the first replacement for Die Sipunculiden, eine systematische Monographic, the 1883 monograph by Selenka, de Man, and Biilow. The Introduction gives a concise overview of the phylum (also see E. Cutler, 1989), together with a brief history of the group, useful "how-to" information, and a glossary.