X INTRODUCTION. 



ducted, to obtain new facts and evidence concerning the origin of species. 

 This investigation has continued to occupy the larger share of my time dur- 

 ing these years and is in no wise complete, but I venture to present in this 

 contribution a first report of progress and a statement of some of the results 

 obtained in some directions up to the present time. 



In this contribution have been brought together data concerning evolution 

 in the genus Lcptinotarsa Stal as gathered from various sources and in as far 

 as it applies in the origin of species. In general, the evidence herein pre- 

 sented has been derived from three sources: (i) its natural history, including 

 distribution and cecology, variations, habits, and instincts; (2) development; 

 (3) experiment. In the account herein presented I have in general followed 

 the order in which the investigation has evolved during the past decade, and 

 the conclusions drawn at the end rest upon data and evidence converging 

 from diverse sources and obtained as a result of long observation. The 

 correctness of my conclusions can be determined only by time and added 

 investigation. 



W. L,. Tower. 



The University of Chicago, 



Hull Zoological Laboratory, 



January 30, 1906. 



