Endeiolepis

Endeiolepis is an extinct jawless fish that lived during the Late Devonian period, similar to that of living lampreys for its gill pouches, but "Endeiolepis" had an unusually large number of gill pouches. Also, "Endeiolepis" was described as being quite similar to "Euphanerops", the main difference being a long series of elongated scales forming a ventrolateral protuberance on each side of Endeiolepis’ body. "Endeiolepis" had a strongly heterocercal tail.
References.
^ Discoveries of "Endeiolepis"