10 



larger than any of the class yet found in the old world. The 

 Carboniferous Amphibians were abundant in the swampy trop- 

 ical forests of that period, and their remains have been found 

 imbedded in the coal then deposited, as well as in hollow 

 stumps of the trees left standing. 



The principal genera of this group from American Car- 

 boniferous rocks, are, Sauropus, known only from footprints, 

 Bcqyhetes, Dendrerpeton, Hylonomus, Rylerpeton, Raniceps, Pelion, 

 Leptophr actus, Molgophis, Plyonius, Amphibamus, Cocytinus, and 

 Geraterpeton. The last genus occurs also in Europe. Certain of 

 these genera have been considered by some writers to be more 

 nearly related to the Lizards, among true reptiles. Some other 

 genera known from fragmentaiy remains or footprints in this 

 formation have likewise been referred to the true reptiles, but 

 this question can perhaps be settled only by future discoveries. 



No Amphibia are known from American Permian strata, but 

 in the Triassic, a few characteristic remains have been found. 

 The three genera, Dictyocephalus, Dispelor and Pariostegus, have 

 been described, but, although apparently all Labyrintho- 

 donts, the remains preserved are not_sufficient to add much to 

 our knowledge of the group. The Triassic foot-prints which 

 have been attributed to Amphibians are still more unsatis- 

 factory, and at present no important conclusions in regard to 

 this class can be based upon them. Prom the Jurassic and 

 Cretaceous beds of this Continent, no remains of Amphibians 

 are known. A few only have been found in the Tertiary, 

 and these are all of modern types. 



The Amphibia are so nearly allied to the Ganoid fishes, that 

 we can hardly doubt their descent from some member of that 

 group. With our present limited knowledge of the extinct 

 forms, however, it would be unprofitable to attempt to trace in 

 detail their probable genealogy. 



The authors to whom especial credit is due for our knowl- 

 edge of American fossil Fishes and Amphibians, are New- 

 berry, Leidy, Cope, Dawson, Agassiz, St. John, Gibbes, Wy- 

 man, Redfield, and Emmons, and the principal literature of the 

 subject will be found in their publications. 



