OF WASHINGTON. 333 



ancestors of the Diptera. There is apparently a close relation 

 ship between these insects and certain Tipulidce. 



In my diagram No. 2, I have attempted to show the develop 

 ment and relationship of the different families of the Hymerioptera, 

 and to illustrate how the phytophagous species, whose larvae 

 are furnished with legs, in time gave place to higher and more 

 specialized forms, whose larvae are apodous. 



I consider the Tenthredinidae to be the lowest of hymenop- 

 terous insects, and from these in time were evolved on one hand 

 the Cephidae and Oryssidas, on the other hand the Uroceridae. 



From the latter probably evolved the Braconidae and Ichneu- 

 monidae, in which the egg-boring apparatus is usually well 

 developed. From the Oryssidae were evidently evolved other 

 forms, in which the egg-boring apparatus becomes variously 

 modified and gradually develops into a true sting, and from 

 which in time came the true aculeates wasps, bees, etc. It is 

 the stem of three or four different families. 



The family Stephanidse is evidently a branch of the Oryssidae, 

 with strong braconid affinities. The Cynipidae, Proctotrypidae, 

 and Evaniidae also had a common origin and in time evolved 

 other forms. 



From the Cynipidae came the Chalcididae, a recent type ; while 

 from the Proctotrypidae, which I believe represent some of the 

 most ancient types of hymenopters, we have a distinct line of 

 descent into the Scoliidae, Mutillidae, and the higher Aculeata. 



My diagram will sufficiently show my conception of the rela 

 tionship of these families, and I will therefore close with a brief 

 synopsis of a new classification of these insects, based upon their 

 relationship as illustrated in my diagram. 



