684 



HISTORICAL GEOLOGY. 



tracks on so small an area show that the Amphibians of the period were in 

 great numbers. 



1113. 



€> ^ ^ ^ €>D 



1114. 



1115. 



1116. 



Footprints op Amphibians. — Fig. lllS, Nasopus caudatus ; 1114, Limnopus vagus ; 1115, Dromopus agilis ; 



1116, Baropus lentus (Xj'j). Marsh, '94. 



LIFE OF THE PERMIAN PERIOD. 



Plants. — The vegetation of the Upper Barren Coal-measures or Permian 

 strata of Pennsylvania and West Virginia (page 651), is characterized, as 

 shown by Fontaine and White, by the absence of Lepidodendrids ; by the 

 rarity of Sigillarice, only two being known ; by the large number of species of 

 Perns (over 30) of the genus Pecopteris, some arborescent, and, only a third 



