Diptera or Hymenoptera, the larvae of the Coleoptera, or the
caterpillars of the Lepidoptera, still less any bearing even a distant
resemblance to the quiescent pupae of these animals. The pupae, indeed,
cannot at all be regarded as members of an original developmental
series, the individual stages of which represent permanent ancestral
states, for an animal like the mouthless and footless pupa of the
Silkworm, enclosed by a thick cocoon, can never have formed the final,
sexually mature state of an Arthropod.

In the development of the Insecta we never see new segments added to
those already present in the youngest larvae, but we do see segments
which were distinct in the larva afterwards become fused together or
disappear. Considering the parallelism which prevails throughout organic
nature between palaeontological and embryonic development, it is
therefore improbable that the oldest Insects should have possessed fewer
segments than some of their descendants. But the larva of the
Coleoptera, Lepidoptera, etc., never have more than nine abdominal
segments, it is therefore not probable that they represent the original
young form of the oldest Insects, and that the Orthoptera, with an
abdomen of eleven segments, should have been subsequently developed from
them.

Taking into consideration on the one hand these difficulties, and on the
other the arguments which indicate the Orthoptera as the order most
nearly approaching the primitive form, it is my opinion that the
"incomplete metamorphosis" of the Orthoptera is the primitive one,
INHERITED from the original parents of all Insects, and the "complete
metamorphosis" of the Coleoptera, Diptera, etc., a subsequently ACQUIRED
one.)