5 i8 THE POPULAR SCIENCE MONTHLY. 



in the Coal-Measures, and show that the Labyrinthodonts differed in 

 important particulars from all modern Amphibians, the group which 

 includes our frogs and salamanders. Some of these ancient animals 

 resemble a salamander in shape, while others were serpent-like in form. 

 None of those yet discovered were frog-like, or without a tail, although 

 the restored Labyrinthodont of the text-books is thus represented. 

 All were protected by large pectoral bony plates, and an armor of 

 small scutes on the ventral surface of the body. The walls of their 

 teeth were more or less folded, whence the name Labyrinthodont. 

 The American Amphibians known from osseous remains are all of mod- 

 erate size, but the footprints attributed to this group indicate animals 

 larger than any of the class yet found in the Old World. The Car- 

 boniferous Amphibians were abundant in the swampy tropical 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 Carboniferous 

 rocks are Sauropus, known only from footprints, Baphetes, Den- 

 drerpeton, Hylonomus, Hylerpeton, Paniceps, Pelion, Leptophr actus, 

 Molgophis, Ptyonius, Amphibamus, Cocytinns, and Ceraterpeton. 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 frag- 

 mentary 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, I)isp>elor, and Pariostegus, have been described, 

 but, although apparently all Labyrinthodonts, the remains preserved 

 are not sufficient to add much to our knowledge of the group. The 

 Triassic footprints which have been attributed to Amphibians are still 

 more unsatisfactory, and at present no important conclusions in regard 

 to this class can be based upon them. From the Jurassic and Creta- 

 ceous 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 knowledge of 

 American fossil Fishes and Amphibians, are Newberry, Leidy, Cope, 

 Dawson, Agassiz, St. John, Gibbes, Wyman, Kedfield, and Emmons, 

 and the principal literature of the subject will be found in their pub- 

 lications. 



