No. 376.] THE WINGS OF INSECTS. 253 
VI. THE VENATION OF THE WINGS OF LEPIDOPTERA. 
= 
In the order Lepidoptera the primitive type of wing venation 
is well preserved in certain of the Jugate. This is shown in 
Sthenopis (Fig. 24). In the species figured here, the devia- 
tions from our hypothetical type are few. In the fore wing, 
veins M4 and Cz: coalesce for the greater part of their length, 
and one of the anal veins has been lost. In the hind wing, 
veins M4 and Cz: anastomose, but separate near the margin of 
the wing.! 
In the Frenatz we find the primitive type well preserved in 
the fore wings of the more generalized forms. The most strik- 
ing departure from our hypothetical type is the fact that the 
Uses 
Fic. 24. — Wings of Sthenopis. 
media is never more than three-branched;? and this is true 
also of the media of the hind wings. The wings of Prionoxystus 
l This is not true of the genus as a whole; usually these veins coalesce in the 
hind wings as in the fore wings. 
? With our present knowledge it is impossible to determine the way that vein 
M, has disappeared in the Frenatæ. We have seen no indication that it coalesces 
with vein C, as in Sthenopis, for in all pupz of this suborder that we have exam- 
ined the medial trachea is only three-branched. We are obliged, therefore, to 
omit any further reference to this vein in the discussion of this order. 
