Saccopharyngiformes

Saccopharyngiformes: Highly aberrant fishes, lacking symplectic bone, opercular bones, branchiostegal rays, scales, pelvic fins, ribs, pyloric caeca, and swim bladder; caudal fin absent or rudimentary; gill openings ventral; dorsal and anal fins long; jaws and hyomandibular greatly elongate, attached to neurocranium by only one condyle; leptocephalous larvae deep-bodied with myomeres V-shaped and not W-shaped. Like anguilliforms, they may spawn once and die.
 * See Fishbase

Families in this order:
 * Cyematidae
 * Eurypharyngidae
 * Monognathidae
 * Saccopharyngidae