as natural
selection increased in successive generations the size and weight of
its body, its legs were used more, and its wings less, until they became
incapable of flight.

Kirby has remarked (and I have observed the same fact) that the anterior
tarsi, or feet, of many male dung-feeding beetles are very often broken
off; he examined seventeen specimens in his own collection, and not one
had even a relic left. In the Onites apelles the tarsi are so habitually
lost, that the insect has been described as not having them. 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.
There is not sufficient evidence to induce us to believe that
mutilations are ever inherited; and I should prefer explaining the
entire absence of the anterior tarsi in Ateuchus, and their rudimentary
condition in some other genera, by the long-continued effects of disuse
in their progenitors; for as the tarsi are almost always lost in many
dung-feeding beetles, they must be lost early in life, and therefore
cannot 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 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 genera 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. Wollaston, lie much concealed, until the wind lulls and
the sun shines; that the proportion of wingless beetles is larger on
the exposed Dezertas than in Madeira itself; and especially the
extraordinary fact, so strongly insisted on by Mr. Wollaston, of the
almost entire absence of certain large groups of beetles, elsewhere
excessively numerous, and which groups have habits of life almost
necessitating frequent flight;--these several considerations have made
me believe that the wingless condition of so many Madeira beetles is
mainly due to the action of natural selection, but combined probably
with disuse. For during thousands of successive generations each
individual beetle which flew least, either from its wings having been
ever so little less perfectly