Notacanthiformes

Notacanthiformes: Body eel-like; posteriorly directed spine on dorsal edge of rear of maxilla; premaxilla and maxilla bordering upper jaw; gill membranes separate; pectoral fins relatively high on body; pelvic fins abdominal, with 7-11 rays (the two fins are usually connected by a membrane); anal fin base long and merged with what remains of the caudal fin; caudal fin skeleton reduced or absent; tail easily regenerated when lost; branchiostegal rays 5-23; swim bladder present. Some have photophores.
 * See Fishbase

Families in this order:
 * Halosauridae
 * Notacanthidae