No. 378.] THE WINGS OF INSECTS. 423 
that it is not to be expected that the trachez will preserve their 
primitive arrangement under these conditions. This brings us 
to the conclusion, already announced, that in determining the 
homologies of the wing-veins in the Hymenoptera we are 
forced to base our conclusions on a study of the veins them- 
selves, and that a method of study which is of the highest 
importance in determining the homologies of the wing-veins in 
many other insects, is of little use here for this special purpose. 
We have pointed out a striking difference in the tracheation 
Fic. 48. — Wings of a young pupa of Apis. 
of the fore wings of Tremex and of Apis. An equally striking 
difference may exist between the fore and hind wings of the 
Same insect. Thus in the pupa of Tremex (Fig. 46) the main 
stem of the radial trachea traverses the subcosta in the fore 
wing; while in the hind wing it retains its primitive position. 
In more specialized members of the order, as in the Ichneumon- 
flies, even less of the primitive arrangement of the tracheze is 
preserved. But a further discussion of this phase of the ques- 
tion would not be profitable here. 
XI. THE VENATION OF THE WINGS OF EMBIID. 
The systematic position of the family Embiidz is a question 
regarding which there is much difference of opinion. We do 
