A.nimals Before Man 



mouites, are just starting in the shape of rather 

 small and plain shells called Cfoniatites, whose 

 successors were to become among the largest, 

 handsomest, and most noteworthy of shell-bear- 



2 



Stylonurus and eurypterus, showing the structure 

 of the under side. 



ing animals. Crustaceans, however, are still 

 among the rulers of the -sea, for the strange 

 eurypterids at this time reached the maximum 

 of size, Stylonurus and Pterygotus (see plate 

 I) attaining a length of five or six feet, al- 



76 



