iv INTRODUCTION. 



All of Part First is original. In preparing objects of 

 natural history I have in a great degree invented methods 

 of my own, and have not given in this work a single 

 one that I have not tested and proved equal to all oth- 

 ers, if not superior. To avoid confusion, I have given 

 only the method which experience has taught me to be 

 the best. 



In this connection my thanks are due to Mr. E. L. 

 Weeks, whose excellent illustrations will be found to add 

 greatly to the value of the work. 



