AMPHIBIA. 233 



these prints to the shape of the human hand that the unknown 

 animal which had produced them was christened the " Cheiro 

 therium " (Gr. cheir, hand ; ther, beast). Further researches, 

 however, showed that these footprints were produced by 

 various species of large Amphibians, to which the name of 

 Ldbyrinthodontia was applied, in consequence of the compli- 

 cated microscopic structure of the teeth. These extinct Am- 

 phibians are known to have existed at the time of the Coal, 

 but they are most characteristic of the period known to geolo- 

 gists as the Trias. 



