n.superclass of eel-shaped chordates lacking jaws and pelvic fins: lampreys; hagfishes; some extinct forms

同義詞：superclass Agnatha

1. Agnatha represents the most primitive group of vertebrates in the evolutionary tree.
   無頜類綱代表了進(jìn)化樹中最原始的脊椎動(dòng)物群體。
2. The study of Agnatha helps scientists understand the early development of vertebrate features.
   研究無頜類綱有助于科學(xué)家理解脊椎動(dòng)物特征的早期發(fā)展。