HISTORICAL REVIEW 



II 



In 1899 appeared a description of the genus Dimetrodon by Baur and 

 Case; in this the genus Ophiacodon^ considered by Marsh as a reptile, was 

 referred to the Amphibia (l). 



In 1900 Case undertook a redescription of the vertebrates from Illinois 

 (11) and the bones from this locality were figured in his paper for the first 

 time. No new forms were described, but the genus Peplorhina, abandoned 

 by Cope, was re-established. 



Two years later (12) the same author described more fully the vertebrse 

 of Lysorophus tricarinatus; they were still regarded as reptilian. 



In 1902, Hay's "Catalogue of the Fossil Vertebrates of North America" 

 appeared as Bulletin 179 of the U. S. Geological Survey (54). His classifica- 

 tion of the fish and Amphibia is as follows: 



Class Elasmobranchii. 

 Subclass Plagiostomata. 

 Superorder Icthyotomi. 



Family Pleuracanthidcs. 

 Genus Diacranodus 

 {Diplodus). 

 Pleuracanthus. 

 Orthacanthus. 

 Superorder Euselachii. 



Family Petalodontidee. 

 Genus Janassa. 



Thoracodus. 

 Icthyodorulites, 

 Ctenacanthus. 

 Class Pisces. 



Subclass Azygostei. 

 Superorder Dipnoi. 

 Order Sirenodei. 



Family Ctenodontida. 

 Genus Sagenodus {Cteno- 

 dus, Ptyanodus). 

 Gnathorhiza. 

 Family Ceratodontidce. 

 Genus Ceratodus. 



Class Pisces — continued. 

 Subclass Teleostomi. 

 Superorder Rhipidistia. 

 Family Osteolepida. 

 Genus Parabatrachus 



(Ectosteorhachis). 

 Superorder Actinopteri. 

 Order Chondrostei. 

 Family Platysomidce. 

 Genus Platysomus. 

 Class Batrachia. 



Suborder Microsauria. 

 Family Diplocaulida. 

 Genus Diplocaulus. 

 Suborder Apcecospondyli. 

 Family Archegosauridce. 

 Genus Trimerorhachis. 

 Dissorophus. 

 Family Cricotida. 

 Genus Cricotus. 

 Family Eryopidce. 



Genus Eryops {Parioxys, 

 Rhachitomus, Epi- 



cordylus). 

 Anisodexis. 

 Acheloma. 



In 1902 (4) Broili published a preliminary account of the skull of Diplo- 

 caulus, in which he proposes to renew the family Diplocaulidee and place it 

 in the Amphibia where it belongs, considering that Cope had not made the 

 correction. He proposes as a classification: 



Lepospondyli. 



Family Microsauridee Dawson. 

 Aistopodida Miall. 

 Diplocaulidce nom. nov. 



In 1903 Case described a new species of Eryops, E. lotus, and a species of 

 Zatrachys,Z.crucifer (14). 



