Among the numbers of the bat species, which were neither named nor
known, we indicated some by names derived from foreign languages, and
others by denominations drawn from their most striking characters. We
have called one the _Horse-shoe Bat_, from the exact resemblance the
fore-part of its face bears to a horse-shoe, and the animal in question
we have called the Javelin Bat, (_fig. 177._) from a sort of membrane
on its nose which perfectly resembles the head of an ancient javelin,
or spear. Though this character alone is sufficient to distinguish it
from all other bats, yet we may add, that it has scarcely any tail,
that its hair and size are nearly like the common bat, but that instead
of having six incisive teeth in the lower jaw, it has only four. This
species of bat is very common in America, but is never found in Europe.
There is another bat in Senegal, which has also a membrane upon its
nose, not in the form of a horse-shoe, or javelin, as in the two
bats we have just mentioned, but in the shape of an oval leaf. These
three bats, being of different climates, are not simple varieties but
distinct and separate species. M. Daubenton has given the description
of the Senegal bat, under the name of the _leaf bat_, in the Memoirs of
the Royal Academy of Sciences, 1759, p. 374.
Bats which have great affinities to birds, by the power of flying,
and the strength of their pectoral muscles, seem to resemble them
still more in these membranes, or crests, which they have on their
faces. These redundant parts, which, at first sight, seem only to be
superfluous deformities, are real characters which fill up the visible
shades between these flying quadrupeds and birds; for most of the
latter have crests, or membranes, about their beaks and heads, which
seem in every respect as superfluous as those of the bats.