The Descent of Man

from Leconte's 'Introduction to Entomology,'
pp. 101, 143.), on the dorsal surface of the abdomen.
In Oryctes it is seated on the propygidium;
and, according to the same entomologist,
in some other Dynastini, on the under
surface of the elytra. Lastly, Westring states
that in Omaloplia brunnea the rasp is placed on
the pro-sternum, and the scraper on the metasternum,
the parts thus occupying the under
surface of the body, instead of the upper surface
as in the Longicorns.
We thus see that in the different coleopterous
families the stridulating organs are wonderfully
diversified in position, but not much in
structure. Within the same family some species
are provided with these organs, and others are
destitute of them. This diversity is intelligible, if
we suppose that originally various beetles made
a shuffling or hissing noise by the rubbing
together of any hard and rough parts of their
bodies, which happened to be in contact; and