fest 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. Wollaston, lie much concealed, until the
wind lulls and the sun shines; that the proportion of wingless beetles
is larger on the exposed Desertas than in Madeira itself; and especially
the extraordinary fact, so strongly insisted on by Mr. Wollaston, that
certain large groups of beetles, elsewhere excessively numerous, which
absolutely require the use of their wings, are here almost entirely
absent. These several considerations make me believe that the wingless
condition of so many Madeira beetles is mainly due to the action of
natural selection, combined probably with disuse. For during many
successive generations each individual beetle which flew least, either
from its wings having been ever so little less perfectly developed or
from indolent habit, will have had the best chance of surviving from not
being blown out to sea; and, on the other hand, those beetles which most
readily took to flight would oftenest have been blown to sea, and thus
destroyed.

The insects in Madeira which are not ground-feeders, and which, as
certain flower-feeding coleoptera and lepidoptera, must habitually use
their wings to gain their subsistence, have, as Mr. Wollaston suspects,
their wings not at all reduced, but even enlarged. This is quite
compatible with the action of natural selection. For when a new insect
first arrived on the island, the tendency of natural selection to
enlarge or to reduce the wings, would depend on whether a greater number
of individual