Figure 4: Cyclostomes. A, a hagfish, Eptatretus sp (about 60 cm). B, a lamprey, Petromyzon marinus (about 50 cm). C, ammocete larva of P. marinus (about 14 cm). D, a Lower Cambrian cyclostomatous tadpole, Didazoon haoae (about 6 cm). (A from 26, B from 27, C from 28, D from 29).