In some other genera
they are present, but in a rudimentary condition. In the Ateuchus or
sacred beetle of the Egyptians, they are totally deficient. The evidence
that accidental mutilations can be inherited is at present not decisive;
but the remarkable cases observed by Brown-Sequard in guinea-pigs, of the
inherited effects of operations, should make us cautious in denying this
tendency. Hence, it will perhaps be safest to look at the entire absence
of the anterior tarsi in Ateuchus, and their rudimentary condition in some
other genera, not as cases of inherited mutilations, but as due to the
effects of long-continued disuse; for as many dung-feeding beetles are
generally found with their tarsi lost, this must happen early in life;
therefore the tarsi cannot be of much importance or be much used by these
insects.
In some cases we might easily put down to disuse modifications of structure
which are wholly, or mainly due to natural selection. Mr. Wollaston has
discovered the remarkable fact that 200 beetles, out of the 550 species
(but more are now known) inhabiting Madeira, are so far deficient in wings
that they cannot fly; and that, of the twenty-nine endemic genera, no less
than twenty-three have all their species in this condition! Several facts,
namely, that beetles in many parts of the world are very frequently blown
to sea and perish; that the beetles in Madeira, as observed by Mr.
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