646 



Proceedings. 



times when the Permian strata were being formed. I would 

 observe, however, that this pause in the abundance of hfe, and 

 the subsequent pause at the close of the Cretaceous period, 

 were probably not so marked as would appear from Professor 

 Phillips's diagram, which was prepared some thirty years ago 

 in accordance wuth the facts then known. Since then ex- 

 tensive beds in North America have been discovered containing 

 fossils which partially bridge the gap between the Cretaceous 

 and Tertiary strata, and others in Bohemia w^hich in some 



degree perform a similar office in respect to the gap between 

 the Permian and Triassic strata. Still, the general facts re- 

 main unaltered by these later discoveries. Then the strata of 

 the Secondary or Mesozoic period were deposited, and they 

 contain records of a time when the waters swarmed with 

 varied life, and the air with winged inhabitants. The salient 

 feature of this period is the appearance of the great saurians, 

 and the teeming life in water and air. There is also an advance 



