FIG. 8.10. Silurian trilobites. (Reprinted by permission from Texf- 

 book of Geology, Part II, Hisforical Geology, by Louis V. Pirsson and 

 Charles Schuchert, published by John Wiley & Sons, Inc., 1915, 

 p. 667.) 



FIG. 8.11. Silurian eurypterid. 1, dorsal view. 2, ventral view. (Re- 

 printed by permission from Textbook of Geology, Part II, Hisforical 

 Geology, by Louis V. Pirsson and Charles Schuchert, published by 

 John Wiley & Sons, Inc., 1915, p. 675.) 



