Noun | 1. | ![]() agnathan, jawless fish, jawless vertebrate - eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms family Myxinidae, Myxinidae - slime-producing marine animals: hagfishes Myxine glutinosa - typical hagfish eptatretus - a fossil hagfish of the genus Eptatretus Myxinikela siroka - fossil hagfish of the Pennsylvanian period (c. 300 million years ago) that resembled modern hagfishes |