n.
无颚类脊椎动物

[ noun ]
superclass of eel-shaped chordates lacking jaws and pelvic fins: lampreys; hagfishes; some extinct forms
<noun.animal>

Agnatha \Agnatha\ n.
a class of eel-shaped chordates with a cartilaginous skeleton
lacking jaws, scales, and pelvic fins. Among these are the
lampreys and hagfishes. There are some extinct forms.

Syn: class Agnatha.
[WordNet 1.5]