ferous scorpion (Buthus?) closely resembling a species now living
in California, together with another scorpion-like animal, Mazonia
Woodiana, while the Devonian insects described from St. John by Mr.
Scudder, are nearly as highly organized as our grasshoppers and May
flies. Dr. Dawson has also discovered a well developed milleped
(Xylobius) in the Lower Coal Measures of Nova Scotia; so that we must go
back to the Silurian period in our search for the earliest ancestor, or
(if not of Darwinian proclivities) prototype, of insects."

Afterwards[21] the writer, carrying out the idea suggested above,
"referred the ancestry of the Myriopods, Arachnids, and Hexapodous
insects to a Leptus-like terrestrial animal, bearing a vague resemblance
to the Nauplius form among Crustacea, inasmuch as the body is not
differentiated into a head, thorax and abdomen [though the head may be
free from the rest of the body] and there are three pairs of temporary
locomotive appendages. Like Nauplius, which was first supposed to be an
adult Entomostracan, the larval form of Trombidium had been described as
a genus of mites under the name of Leptus (also Ocypete and Astoma) and
was supposed to be adult."

In the same year Sir John Lubbock[22] agrees with Brauer that the groups
represented by Podura and Campodea may have been the ancestors of the
insects, remarking that "the genus Campodea must be regarded as a form
of remarkable interest, since it is the living representative of a
primaeval type from which not only the Collembola (Podura, etc.) and
Thysanura, but the other great orders of insects, have all derived their
origin."

The comparison of the Leptus with the Nauplius, or pre-Zoeal stage of
Crustacea, is much more natural. But here we are met with apparently
insuperable difficulties. While the Nauplius (Fig. 191) has but three
pairs of appendages, which become the two pairs of antennae and
succeeding pair of limbs of the adult, in the Leptus as the least number
we have five pairs, two of which belong to the head (the maxillae and
mandibles) and three to the thorax; besides these is a true heed,
distinct from the hinder region of the body. It is evident that the
Leptus fundamentally differs from the Nauplius and begins life on a
higher plane. We reject, therefore, the Crustacean origin of the
insects. Our only refuge is in the worms, and how to account for the
transmutation of any worm with which we are at present acquainted into a
form