A STUDY OF THE WINGS OF THE TENTHREDINOIDEA. 

 A SUPERFAMILY OF HYMENOPTERA. 



By Alexander Dyer MacGillivray, 



Instructor in Entoinologi/, Vnrnell University. 



INTRODUCTION. 



This is a stud}^ in the phylog-ony of a group of animals based on a 

 stiulv of the modifications of a singh^ organ. It is an attempt to traee 

 tiie course of the changes wrought hy natural selection, an effort to 

 apply the principles of descent to taxonomy. 



Classifications based on the modifications of a single organ are gen- 

 erally imperfect. But on no single organ of any group of animals or 

 plants has the efi'ects of natural selection been written so clearly as on 

 the wings of insects. The record is spread out as on a printed page 

 and only awaits the translator. The taxonomy of several groups of 

 insects based on a genetic study of their wings has been pu])lished, 

 and in every case where phylogenies based on other sets of organs 

 have been made it has been found that they confirm the conclusions 

 derived from a study of the wings. 



The Tenthredinoidea have been carefully studied by many investi- 

 gators. Several classifications have been proposed, but no attempt 

 has been made hitherto to work out an arrangement along- the lines 

 here proposed. In previous groupings a character common to a large 

 number of forms and not common to others has been taken as of high 

 value, while those common to a smaller number of forms as of sub- 

 ordinate value. No account has been taken of the question as to 

 whether these characters include forms of one or of many lines of 

 descent. 



At the outset I wish to express my obligations to Prof. J. H. Corn- 

 stock and Dr. W. A. Riley for constant advice throughout the prepa- 

 ration of this paper; to the authorities of the United States National 

 Museum for the loan of specimens from their collections not otherwise 

 accessible to me, and to Mr. J. Chester Bradley for the privilege of 

 examining a number of species and for looking over the manuscript. 



Proceedings U. S. National Museum, Vol. XXIX— No. 1438. 



569 



