The Lampreys (Petromyzontiformes) - order

(Mesomyzon)
- genera

(Priscomyzon)
- genera

(Hardistiellidae)
- family

(Mayomyzonidae)
- family

(Pipisciidae)
- family

(Geotriidae)
- family

(Mordaciidae)
- family
The Northern Lampreys
(Petromyzontidae)
- family