vi Illustrations. 



Figure 3, p. 144, A reproduced wing in Tremex. 



Figure 4, p. 260, Gneissic rocks at Grandmother Falls, Wis. 



Figuje 5, p. 581, Structural features in Shakopee limestone. 



Figure 6, p. 282, Structural features in Shakopee limestone, possibly 

 Cryptozoon. 



Figure 7, p. 282, Further structural features, possibly Cryptozoon. 



Figure 8, p. 325, Diagrammatic section of the Lower Silurian, (Ordovician) 

 rocks of southeastern Minnesota. 



Fig. 1, p. 390, The decomposition of limestoue and the formation and ac- 

 cumulation of soil. 



Figure 2, p. 391, The decomposition of glacial drift and the formation of 

 soil. 



