304 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
•Neuroptera. Tlie Lepidoptera probably originated from the same group 
from which the Panorpidse and Triclioptera branched off, and we agree 
with the opinion of H. Muller, 150 who maintains that the Lepidoptera 
and Triclioptera “ proceed from a common stock,” though we should sup- 
pose that the Panorpidaj in their larval stage represented forms like the 
ancestral caterpillar. 
The adult structure and larval forms of the Diptera show’ that they 
originated from nearly the same stock as the moths. The most perfectly 
developed Dipterous larvae are those of the Culicidae and Tipulidoe; 
these were probably the primitive forms; the other Dipterous larvae, 
notably the larval Muscidae or maggots, are degradational forms, and 
the lower Diptera appear to have been degraded or degenerate forms. 
The case is different with the Hymenoptera. The saw-fly larvae rep- 
resent apparently the primitive larval form; and from their resem- 
blance to caterpillars and Panorpid larvae, show that the Hymenoptera 
and Lepidoptera may have had a common origin. The footless larvae 
of the parasitic Hymenoptera are correlated with their parasitic mode 
of life, and the similar forms of the larval wasps and bees show that 
from disuse their mouth-parts and legs became aborted, and the immo- 
bile larvae became short and thick-bodied. Hence such larvae should 
be regarded as secondary, adaptive larval types. The high degree of 
specialization of the bees’ mouth-parts, their concentrated bodies and 
4-segmented thorax, with other characters, show that they are the 
highest, most specialized and modern of all insects. 
Note. — I t should be borne in mind that the embryo bee has a pair 
of temporary abdominal appendages on each segment (uromere); so 
also has the Lepidopterous, Coleopterous, and Orthopterous embryo, 
which points back to a common, Scolopendrella-like type; this also pos- 
sibly indicating a still earlier, worm-like, Peripatus-like ancestor for 
Myriopoda and Hexapoda at least, if not Arachnida. For previous dis- 
cussions as to the origin of insects the reader is referred to the writings 
of Fritz Miiller, Brauer, Lubbock, and the author. 
Order II. DERMATOPTEItA. 
Forficulid^e. Plates XXIII, XXIV. 
THE HEAD. 
Forficula twniata Dohrn. (PI. XXI II, tigs. 1-3). The head is horizon- 
tal in position, broad and flat, squarish, the sides being parallel. There 
is a V-shaped epicranial suture, which is more distinct in the larva} of 
this genus and in Labia. The epieranium is otherwise simple; no ocelli. 
The clypeus is simple, being no wider and not much larger than the lab- 
rum. The genal ridge prominent; a broad gular region. Behind the 
160 American Naturalist, v, July, 1871, 288. See also the same magazine, Nov., 1871, p. 7u7-7i3. 
