to speak, between the mandibulate and
haustellate types, but are simply a modification (through disuse) of the
mandibulate type as seen in Neuropterous insects.]

[Footnote 12: Lubbock considers that Papirius should be placed in a
distinct family from Smynthurus, because it wants tracheae. Their
presence or absence scarcely seems to us to be a family character, as
they are wanting in the Poduridae, and are not essential to the life of
these animals, while in other respects Papirius seems to differ but
slightly from Smynthurus.]

[Footnote 13: Dr. Laboulbene has recently, and we think with good
reason, separated Anura maritima from the genus Anura, under the name of
Anurida maritima.]

CHAPTER XIII.

HINTS ON THE ANCESTRY OF INSECTS.

[Illustration: 177. Pentastoma.]

[Illustration: 178. Centipede.]

Though our course through the different groups of insects may have
seemed rambling and desultory enough, and pursued with slight reference
to a natural classification of the insects of which we have spoken, yet
beginning with the Hive bee, the highest intelligence in the vast world
of insects, we have gradually, though with many a sudden step, descended
to perhaps the most lowly organized forms among all the insects, the
parasitic mites. While the Demodex is probably the humblest in its
organization of any of the insects we have treated of, there is still
another mite, which, some eminent naturalists continue to regard as a
worm, which is yet lower in the scale. This is the Pentastoma (Fig. 177,
P. taenioides), which lives in the manner of the tape worm a parasitic
life in the higher animals, though instead of inhabiting the alimentary
canal, the worm-like mite takes up its abode in the nostrils and frontal
sinus of dogs and sheep, and sometimes of the horse. At first, however,
it is found in the liver or lungs of various animals, sometimes in man.
It is then in the earliest or larval state, and assumes its true mite
form, being oval in shape, with minute horny jaws adapted for boring,
and with two pairs of legs armed with sharp retractile claws. Such an
animal as this is little higher than some worms, and indeed is lower
than many of them.

We should also not pass over in silence the Centipedes (Fig. 178,
Scolopocryptops sexspinosa) and Galley worms, or Thousand legs and their
allies (Myriopods), which by their long slender bodies, and great number
of segments and feet, vaguely recall the worms. But they,