Vicinity of Mazon Creek, Illinois. 



325 



directed toward the costal margin. The media in its basal 

 part bends closely toward the radius and is cleft before attain- 

 ing the end of the first quarter of its length. Its anterior 

 main branch continues in a normal way and splits in the apical 

 half; the posterior has the aspect of an oblique cross vein 

 uniting the media with the cubitus. At a certain distance 

 from this point of fusion we see that in the right wing a new 

 separation of the two veins takes place, the branch of the 

 media forming a large terminal fork. In the left wing there is 

 but a temporary separation of the fused veins, which then 

 unite again and remain so to the end. Nevertheless it is pos- 

 sible, but not determinable, that the last fork of the cubitus 

 may take rise from this second medial branch. In this case 

 we would be forced to assume a strong reduction of the cubitus 

 in the left wing in comparison to the right, where this vein 



Fig. 30. 



Fig. 30. Cacurgus spilopterus (left fore wing). xl - 25. 



with its 8 or 9 partly forked branches occupies the whole hind 

 margin. There being only 8 branches in the left wing, their 

 number would be reduced to 6 by counting the apical fork as 

 belonging to the medial vein. 



The anal area is broadly lancet-shaped, limited by an 

 S-shaped vein and seems to have been filled by only a few 

 veins of a similar curve. In all the broader interstices the 

 cross veins are twisted into a moderately regular and polygo- 

 nal network. Irregularly spread about there are to be found 

 in both wings shallow, more or less regular, round bodies of 

 different sizes, situated in darker patches of the wing mem- 

 brane and showing a small groove in the middle. These 

 structures give the impression of membrane thickenings. I 

 probably should have regarded them as extraneous and not 

 pertaining to the insect if they had been observed only in this 



