from Wiktionary, Creative Commons Attribution/Share-Alike License.
- proper noun A taxonomic
classwithin the subphylum Vertebrata— the living jawless fishes: lampreysand hagfishes; the cyclostomes.
from Wiktionary, Creative Commons Attribution/Share-Alike License
Rather "do the _Holocephala_, _Plagiostomata_, and _Cyclostomata_ appear to us to be lower developmental stages individually differentiated, so that the other fully differentiated Vertebrates cannot easily be referred directly to their type" (p. 152, 1838).