SuperClass Agnatha is a division the subphylum vertebrata which has the following characteristics:

• Slender, eel-like body.
• Median fins but no paired appendages.
• Fibrous and cartilaginous skeleton; notochord throughout life.
• Heart with one atrium and one ventricle.
• Dorsal nerve cord with differentiated brain.
• Digestive systems without stomach.
• Sense organs of taste, smell and hearing.
• External fertilization.

Agnatha is considered a superclass made up of the following classes:

• Class Myxini (the hagfishes)
• Class Cephalaspidomorphi (the lampreys)