OF THE HIND WINGS OF HYMENOPTEROUS INSECTS. 
137 
I have examined this apparatus in different genera of Lepidoptcra. The bristle is 
usually not only double or divided and forked from the base, instead of single, but also is 
much weaker in the females than in the males. 
i> v..~. 
3 no affinity in its structure with the hooks on the hind wings of Hymenoptera and 
Aphides here described ; and from its situation at the base of the wing, its flexible and 
elastic character, and from the imperfection of the loop, it can have little effect in keeping the 
wings "in the same line during flight/' or at least an effect very different from that produced 
by the hooks on the margin of the wings of Hymenoptera and Aphides, which, wherever 
they may commence, always reach to near the middle of the wing, and are thus able to act 
with considerable power in connecting the two wings and keeping them in place. 
I cannot believe that the use of this apparatus in the Lepidoptera has yet been disco- 
vered, or that it is of the same nature with that of the hooks here described. Perhaps 
the name of " spring," which Mr. Haworth gives to it, may best illustrate its use. 
Fig. 
Fig. 
Fig. 
Fig. 
EXPLANATION OF THE PLATES. 
Tab. 16. 
Hind Wings of Hymenoptera Terebrantia, Latr., and Aphis. 
1. Allantus (N. America), a. the 16 distal hooks and the first sub-basal. 
Fig. 2. Cephus pygmceus. 
Fig. 3. Hylotoma 
a. the distal hooks 
Fig. 4. 
5. 
6. 
, B. The distal hooks. 
ustulata. Distal hooks, and, i and 2. ? sub-basal hooks. 
femoralis. a. tip of wing. 
7. Perga. 
Fig. 8. Pterygophorus. a. base of wing : b. i, 10. distal hooks ; i, 3. sub-basal hooks. 
Fig. 9. Tenthredo viridis. a. the distal and three first sub-basal hooks ; i, 2, 3. end of nerve 
0. Tenthredo, sp. n. ? 1, 2, 3. end of nerves. 
1. Sciapteryx costalis. a. end of costal nerve. 
2. Xyphidria Droi 
3. Sirex Juvencus. 
3 
W 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 20. Pimpla, England. 
Fig. 21. 
«. sub- basal hooks 
4. Cryptus, Europe. 
5 . Cryptus, England. Scar of sub-basal hook 
6. Mesostenus. 
7* Ophion obscurus. 
a. the distal hooks ; b. sub-basal hooks 
8. 
combustus. sub-basal hooks. 
9. Paniscus (England), a. sub-basal hooks 
N 
distal hooks. 
Fig. 
22. Osprynchotus 
a. base of costal nerve 
Fig. 23. Trogus. 
Fig. 24. Chalets, a. distal hooks. 
Fig. 25. Chrysis. a. the sub-basal hooks. 
VOL. XXIII. 
T 
