Dichotomous Key/Petromyzonidae

This is a Dichotomous Key for the Family Petromyzonidae.

1

 * Dorsal and caudal fin distinction
 * The dorsal and caudal fins are distinct - Dichotomous Key:Petromyzon
 * The dorsal and caudal fins are not distinct -

2

 * Depth of dorsal fin notch
 * Shallow - Dichotomous Key:Ichthyomyzon
 * Deep - Dichotomous Key:Lampetra