Hay's Catalogue of Fossil Vertebrata of North America contains the next scheme for the classification of the Amphibia which pays especial attention to the extinct forms. His classification is as follows:
Class Batrachia Macartney, 1802.
Order Stegocephali Cope, 1868.
Suborder Microsauria Dawson, 1863.
Family Protritonidæ Lydekker, 1889.
Genera: Amphibamus Cope, Pelion Wym.
Family Molgophidæ Cope, 1875.
Genera: Phlegethontia Cope, Molgophis Cope.
Family Hylonomidæ Fritsch, 1883.
Genera: Hylonomus Dawson, Smilerpeton Dawson, Hylerpeton Owen, Fritschia
Dawson; Brachydectes Cope.
Family Ptyoniidæ Cope, 1875.
Genera: Keraterpeton Huxley, Œstocephalus Cope, Ptyonius Cope,
Ctenerpeton Cope.
Family Tuditanidæ Cope, 1875.
Genera: Tuditanus Cope, Cocytinus Cope.
Family Diplocaulidæ Cope, 1881.
Genus: Diplocaulus Cope.
Lepospondylous Genera of uncertain position: Amblyodon Dawson, Hyphasma
Cope, Eurythorax Cope, Thyrsidium Cope, Pleuroptyx Cope,
Cercariomorphus Cope.
Suborder Apœcospondyli Hay, 1902.
Family Dendrerpetontidæ Fritsch, 1889.
Genera: Dendrerpeton Owen, Baphetes Owen, Platystegos Dawson.
Family Sauropleuridæ Hay, 1902.
Genera: Sauropleura Cope, Leptophractus Cope.
Family Archegosauridæ.
Genera: Trimerorhachis Cope, Dissorophus Cope.
Family Cricotidæ Cope, 1884.
Genera: Cricotus Cope.
Family Anthracosauridæ.
Genus: Eosaurus Marsh.
Family Eryopidæ Cope, 1882.
Genera: Eryops Cope, Ichthycanthus Cope, Zatrachys Cope, Anisodexis Cope,
Acheloma Cope.
Family Mastodonsauridæ Huxley, 1863.
Genera: Mastodonsaurus Jaeger, Eupelor Cope, Pariostegus Cope, Dictyocephalus
Leidy.
Order Urodela.
Genera: Scapherpeton Cope, Hemitrypus Cope.
Order Salientia Laurenti, 1768.
Family Ranidæ.
Genera: Rana Linné, Eobatrachus Marsh.
This classification given by Hay is only for the forms which occur in North America.
[CHAPTER VII.]
CLASSIFICATION OF AMPHIBIA ADOPTED IN THIS WORK, AND A LIST OF THE COAL MEASURES AMPHIBIA FROM NORTH AMERICA.
A few words of explanation will be necessary for an understanding of the following classification. The term Amphibia Linné, 1758, is, according to Stejneger ([550]), the correct term for the entire group, and this term is adopted. The term Stegocephala, formerly used as a group name for the entire Carboniferous, Permian, and Triassic Amphibia, regardless of structure, has been retained as a third subclass. The choice, so far as priority is concerned, between Labyrinthodontia and Stegocephala, is not easy. The terms, however, imply different structures. The labyrinthodonts proper have stereospondylous vertebræ, while the Stegocephala have either temnospondylous or stereospondylous vertebræ; so the latter term has been adopted.
The ordinal terms are those which have been used previously as subordinal, sectional, or family names, with the exception of the new ordinal term "Diplocaulia" ([477]). The term Branchiosauria is well-established, and it is here retained with the definitions previously given. The same may be said for the Microsauria, although Dawson first ([208]) regarded it as a family, though giving the term an ordinal form. The Aistopoda are not entitled to consideration as a group for reasons which are given subsequently. The Temnospondylia and the Stereospondylia, the Embolomeri and the Rachitomi may or may not be good group names, but they have priority, so far as our knowledge of structure goes. They have been retained in their original meanings. They have been variously regarded as sections, superfamilies, groups, and subfamilies.
The following list of species is arranged according to the proposed scheme of classification: