454 Dr. A. Dohrn on Eugereon Boeckingi. 
incomplete metamorphosis will not-hold their ground against 
a sharper examination and criticism of the facts. 
Hickel has also entirely given up this principle of division, 
and retained instead of it the form of the buccal organs, so 
far as they are arranged either for biting or sucking. Whether 
this is a permanent principle must be shown hereafter, when 
more means of observation may be employed than at present. 
Discoveries like Hugereon, in a paleontological direction, and 
the larva of Sisyra (described by Westwood as Branchiotoma 
Spongille, see Gerstiicker and Carus, ‘ Zoologie,’ p. 73), which, 
as I have been informed by Professor Grube, and also find 
repeated in Gerstiicker’s ‘ Handbuch,’ likewise has a sucking 
buccal apparatus, although its imago belongs to the Neuro- 
ptera, are certainly adapted to render the certainty of this mode 
of division somewhat doubtful. However, it is of no con- 
sequence whether or not there is such a principle of division ; 
when we have a knowledge of the ontogenetic and phylo- 
genetic development we can subsequently select any principle 
we like, and employ it for the sake of convenience. For the 
present we must adhere to Hickel’s classification. Hiickel is 
of opinion that the first Protracheate (belonging to the hypo- 
thetically adopted family produced from the Zoépoda, but 
which still united in itself the germs of the Insecta, Arach- 
nida, and Myriopoda), which possessed two developed pairs of 
wings, is to be regarded as the common progenitor of all the 
living and fossil insects known to us, as the apterous forms 
undoubtedly all (?) originate from winged ancestors, and have 
lost their wings by adaptation and secondary generation. The 
development of this progenitor falls in the interval between 
the Silurian and Carboniferous periods, and probably in the 
ante-Devonian period; for we have insects from the Devonian 
as well as from the coal, and these are exclusively Masticantia 
(Orthoptera, Neuroptera, Coleoptera). These Hickel regards 
as the oldest insects, in opposition to the Sugentia, which have, 
branched off from the Masticantia; and this is certainly pro- 
bable when we glance at the ontogenesis of the former. ‘The 
Masticantia he divides into three orders :—Toroptera, Coleo- 
ptera, and Hymenoptera. The Toroptera are the scarcest, 
and combine the Pseudo-Neuroptera, Neuroptera, and Ortho- 
ptera, which are very nearly allied to each other in many re- 
spects, and were formerly only separated by the metamor- 
phosis. As, however, the systematic value of the metamor- 
phosis, as a means of division, has been diminished, these 
former orders are certainly justly united. Hickel thinks that 
the Bie and Neuroptera have been a from the 
Pseudo-Neuroptera—an opinion which obtains a oundation of 
