ADVERTISEMENT. 



The present work is one of a series to be published by the 

 Smithsonian Institution for the purpose of facilitating the study 

 of certain branches of the Natural History of North America 

 which appear to require special aid. It has been prepared, at the 

 request of the Institution, by Dr. LeConte, to whom science is 

 much indebted for thus devoting his time to the preparation of an 

 elementary book, intended to introduce others to a field in which 

 he has himself beeu so successful a pioneer. 



JOSEPH HENRY, 



Secretary S. I. 

 Smithsonian Institution, 



Washington, May, 1861. 



The preceding advertisement was written and published with 

 page 1—208, in May, 1861. Since then, pages 209—218, com- 

 pleting Part I of the present work, have been prepared and are 

 now published. 



The second and concluding part of the work will contain the 

 families embraced in the divisions Tetramera and Trimera of the 

 older authors. Some time will, however, necessarily elapse before 

 it can be prepared by Dr. LeConte. 



J. H. 



February, 1862. 



ACCEPTED FOR PUBLICATION, OCTOBER, 1860. 



PHILADELPHIA : 

 COLLINS, PRINTER. 



