Animals Before Man 



marked as in the frog, but more like that ^vhich 

 changes the salamander-like Siredon of Mexico 

 into the air-breathing Amblystoma, the one 

 being a gill-bearing creature with a compressed 

 tail, the other without gills and with a round 

 tail. 



Our knowledge of these Carboniferous am- 

 phibians, and particularly of the smaller forms, is 

 mostly derived from the abundant and well-pre- 

 served examples found in Europe ; for while the 

 ironstone nodules of Mazon Creek, 111., have 

 yielded up some fine little specimens, the great- 

 er portion of the fossils from our coal-measures 

 are but poorly preserved. The Permian rocks 

 of Texas, however, have given us a number of 

 imperfect specimens, and a few real prizes, 

 such as the skull of Eryo jds, shown on page 118, 

 though nothing to compare with some of the 

 material that has been found in Europe. 



Many, or most, of the Stegocephala were 

 protected to some extent by armor, but, con- 

 trary to the usual custom, this was more often 

 found on the under side of these animals than 

 on their backs. Still some of the smaller 



120 



