1883.] On the Genealogy of the Insects. 935 
hints which may throw light on ‘the origin of the Hemiptera. 
They are evidently the offshoot of a stock which had an incom- 
plete metamorphosis, or they may have descended directly from 
a modified Campodea-like ancestral form. 
VI. Neuroptera——The members of this order are, excepting 
perhaps the Hemiptera, the most modern and least composite or 
synthetic forms that we have yet met with in our ascent up the 
insect series from the Thysanura. Moreover, in them for the 
first time do we meet with worm-like, cylindrical-bodied larve, 
or what we have called eruciform larve.1 These larve are sec- 
ondary forms, derived, as Fritz Miiller has in a general way sug- 
gested, from those larve which have an incomplete metamorpho- 
sis. By what line of descent, however, the lowest group of Neu- 
roptera, viz., the Sialidz, arose, it would be difficult to say. The 
earliest winged insects were probably terrestrial ; the aquatic lar- 
val forms of the Sialidz are evidently derivations from Campo- 
dea-like terrestrial larvæ. But how the perfect metamorphosis 
with the quiescent pupa of the Neuroptera was brought about, 
is indeed a problem. It is evident, however, that the eruciform 
larva is a derivation from a Thysanuran* type, as first stated by 
Fritz Miller. 
It seems to us that a consideration of the diverse larval forms 
which occur in the present order, throws some light on the ori- 
gin of a complete metamorphosis in insects in general. In the 
Sialidæ, as the larva of Corydalis, or Semblis, we have a Campo- 
dea-form provided with gills, and with the mouth-parts adapted for 
Seizing and biting its prey. The terrestrial larve of the Hemer- 
obiidz are evidently modifications of the Sialid larval form; the 
differences of structure in them, such as the long slender mandi- 
bles and maxilla and the short abdomen, being the result of their 
carnivorous habits, and their being obliged to climb up the stems 
of plants or to walk over the leaves after smaller insects. Under 
Such circumstances the body would become shorter and more 
concentrated, and the legs well developed. In the Trichoptera, 
* See “ Our Common Insects,” p. 175, 1873. Also the AMERICAN NATURALIST, 
Vol. v, Sept., 1871. 
? We have, in the writings just quoted, called the second class of larvæ Leptiform, 
the Thysanuriform, or Brauer’s expression Campodea-form, is prefer- 
able. The Campodea or primitive Hexapodous form is evidently a derivative form, 
which points back to a common six-footed ancestor of all Tracheata, to which the 
term Leptiform may be applied. 
