Systematics, zoogeography, and ecology of the Priapulida

CONTENTS 1 Introduction.................. 4 1.1 Plan .................. 4 1.2 Material and methods.............. 5 1.3 Acknowledgements............... 6 2 Systematics.................. 8 2.1 Historical introduction.............. 8 2.2 Phylum Priapulida............... 9 2.2.1 Diagnosis................ 10 2.2.2 Classification............... 10 2.2.3 Definition of terms............. 12 2.2.4 Basic adaptive features............. 13 2.2.5 General features.............. 13 2.2.6 Systematic notes.............. 25 2.3 Key to the taxa................ 26 2.4 Survey of the taxa............... 29 Priapulidae................. 29 Priapulopsis ................ 30 Priapulus................. 51 Acanthopriapulus............... 60 Halicryptus ................ 62 Tubiluchidae................. 70 Tubiluchus................. 73 3 Zoogeography and ecology.............. 84 3.1 Distribution................. 84