Full reference: E. L. Yochelson. 1977. Agmata, a proposed extinct phylum of Early Cambrian age. Journal of Paleontology 51:437-454
Parent taxon: Cnidaria according to P. J. Vayda et al. 2025
See also Yochelson 1977
Sister taxa: Annulatubus, Anthozoa, Cambroctoconus, Cambrorhytium, Cloudinidae, Crassitubus, Erniettamorpha, Escumasia, Haootia, Hydroconozoa, Inaria, Liaoningia, Mackenziidae, Mawsonites, Medusae, Medusozoa, Melanofurcata, Melanosteus, Melanostylus, Myxozoa, Priscapennamarina, Pywackia, Quadratitubus, Ramellina, Ramitubus, Sekwitubulus, Sinocyclocyclicus, Spatangopsis, Syringophyllum, Thaumoptilon, Vauzutsubua, Zolotytsia
Subtaxa: Salterella Salterellidae Volborthellida Volborthellidae
Distribution:
• Ordovician of United States (1: Tennessee collection)
• Cambrian of Argentina (1), Canada (11: Labrador, Neufundland and Labrador, Newfoundland and Labrador, Quebec, Yukon, Yukon Territory), Czechia (3), Denmark (1), Greenland (9), Mexico (2), Norway (6), Sweden (3), the United Kingdom (8), United States (27: California, Nevada, Pennsylvania, Virginia)
• Caerfai of Canada (1: Northwest Territories)
• Waucoban of Greenland (1), United States (1: California)
Total: 75 collections including 81 occurrences