A list of fishes of the mainland of North and Middle America recorded from both fresh water and sea water

For purposes of this paper a euryhaline fish is defined as one that is found in both freshwater and sea water under natural conditions. A list is compiled of all fishes, including cyclostomes and elasmobranchs, that have been recorded from both habitats in North and Middle America, north of the southern boundary of Panama. The list is divided into four parts: Pacific Coast south to Mexico, west coast of Mexico southward, Atlantic Coast to the southern part of the east Florida Coast, and the east coast of Mexico southward. The Gulf Coast of the United States is left out because all but three species of fishes from that region are included on other divisions of the list.