Petromyzontidae

Petromyzontidae are a family of lampreys native to the Northern Hemisphere, comprising the vast majority of living lampreys. Petromyzontids have the highest number of chromosomes (164–174) among vertebrates.

Genera

 * Caspiomyzon
 * Entosphenus
 * Eudontomyzon
 * Ichthyomyzon
 * Lampetra
 * Lethenteron
 * Petromyzon
 * Tetrapleurodon