No. 376.] THE WINGS OF INSECTS. 239 
The wings of a nymph of Tzeniopteryx (Fig. 9) show a slightly 
different modification of the type. The costal trachea is well 
preserved. The subcosta is typical. The radial sector is reduced 
Fic. 9. — Wings of Tzniopteryx, nymph. 
even more than in Nemoura, the coalescence of veins R2+3 
and 4+5 having extended to near the margin of the wing; the 
carrying of this process a little farther would reduce the radial 
Sc Se. 
A 
Fic. 10. — Wing of Txniopteryx, adult. 
sector to an unbranched condition, which is what has happened 
in some species of this genus (Fig. 10). The media is three- 
branched in the fore wing and two-branched in the hind wing, 
but in the hind wing vein M3+4 coalesces with vein Cur. The 
