Бутия
Ctenaspidae encompasses the ctenaspids, ("Ctenaspis", "Arctictenaspis" and "Zaphoctenaspis"), and the allocryptaspids ("Boothiaspis", "Allocryptaspis" and "Alainaspis"). "Boothiaspis", from the Boothia Peninsula, was originally described as a Canadian amphiaspidid.