NO. U38. WINGS OF THE TENTHREDINOIDEA—MacGILLIVRAY. 647 



4. The progressive coalescence of the base of media and radius 

 toward the middle of the wing- and, coordinated with this, the progres- 

 sive migration of the medio-cubital cross-vein toward the point of 

 separation of radius and media to form a transverse support for the 

 stigma. 



5. How all the types of anal cells found in the superfamily Ten- 

 thredinoidea have been developed from the form of this area found 

 in the generalized families. 



6. The veins of the hind wing have been homologized with those of 

 the front wing and all the marked modifications occurring in the 

 superfamil}" discussed. 



7. An attempt has been made to show that all the modifications in 

 wing topogi^aph}^ are directly dependent on the efficiency of the wing 

 as an organ of flight, and that this efficiency is due to the arrangement 

 of the veins in such a manner as to stift'eii the areas of the wing sub- 

 ject to the greatest stress. 



8. The venational distinction of the Tenthredinoidea from the other 

 superfamilies of the Hymenoptera has been pointed ou'. 



tt. The distinctive characters of the families of the Tenthredinoidea 

 have been considered in detail and their phylogenetic importance 

 indicated. 



10. The loss of the base of the radial sector and its l)earing on the 

 homology of the veins of the wings of the higher Hymenoptera has 

 been discussed. 



11. A classification of the superfamily Tenthredinoidea is given. 

 The sequence of the families and subfamilies, whether generalized or 

 specialized, has been determined by a genealogical study of the differ- 

 ent structural modifications of the wings. 



12. Analytical tables are given for separating the families of the 

 superfamily Tenthredinoidea and of the subfamilies of the family 

 Tenthredinida?. These tables are based on venational characters alone, 

 and are examples of the value of such studies as the one given in the 

 preceding pages. 



13. Front and hind wings of all the generalized genera and examples 

 selected from the numerous other groups are figured and their wing- 

 veins homologized. 



14. All previous classifications have been based on recognition 

 characters and are therefore likely to be artificial. (Ireat use has 

 been made of the form of the antenna and claws, modifications that 

 have arisen independently several times. The foregoing investigation 

 is only a beginning of what needs to be done. Phylogenetic studies 

 should be made of all those structural parts that will indicate anything 

 as to the complete genealog}- of the group. Two such regions are 

 the mouth parts and the structure of the thorax. 



