Genus Ichthyomyzon


Northern brook lamprey - Lampreys are long, slender fish-like animals, lacking lower jaws, which results in a downward facing mouth.


Mountain brook lamprey - The dorsal fin is notched but not separated from the disk, and when expanded, is always narrower than the head.


Silver lamprey - Aside from the obvious lamprey characteristics the dorsal fin may be notched slightly but not divided into two separate parts, all the teeth are well developed and the mouth, when expanded is wider than the head.