缺甲鱼亚纲（Anaspida）是一种已灭绝的原始无颌脊椎动物，生活在志留纪和泥盆纪时期。有古生物学家视牠们为七鳃鳗的祖先。

• 七鳃鳗亚纲(Petromyzontida)/(Hyperoartia)
• 有头动物(Craniata)

For the reptiles, see Anapsida; for the crustaceans, see Anaspididae

Anaspida ("without shield") is an extinct group of primitive jawless vertebrates that lived primarily during the Silurian period, and became extinct soon after the start of the Devonian. They were once classically regarded as the ancestors of lampreys. Anaspids were small marine agnathans that lacked heavy bony shield and paired fins, but have a striking highly hypocercal tail. They first appeared in the early Silurian, and flourished until the early Devonian, where they then disappear from the fossil record.