36 THE MAMMALS, REPTILES, AND FISHES OF ESSEX.
aquatic species. Its habit of haunting water, whether stag-
nant ponds or running streams, flitting with rapid vibrations
of the wings a very few inches above the surface, and appar-
ently spending most of its time of flight there, makes the
description "aquatic" a very exact one.
Those I have endeavoured to keep appeared delicate, and
soon died. Possibly they required aquatic insects, or it
may be they could not bear confinement. The members of
the entire family appear equally unfitted for close captivity,
and I have never succeeded in keeping insectivorous bats
alive for any length of time.
Vespertilio nattereri, Kuhl. Reddish-grey Bat.
This easily-distinguished bat is reputed to be rare. In
the district round Colchester, however, it is one of our com-
monest species. It is recorded by Doubleday (Zool., 1843,
p. 6) as found at Epping, and Newman also notes (Field,
Mar. 14th, 1874, p. 263) that it is not uncommon there. I hear
the peculiar squeaking note of this bat during its evening
flight more frequently than any other in the streets and gardens
of Colchester.
Houses and buildings are its favourite hiding-places in
summer. In winter, cellars, caverns (as those under Colchester
Castle), and similar places are generally chosen. Occasion-
ally, in the late autumn, bats are brought to me which have
been drawn up to the surface in buckets from some of our
deepest wells. From my observation that three out of every
four are of this species, I am led to believe that crevices in
the brickwork of the wells are chosen by them as hyber-
nacula.
Vespertilio mystacinus, Leisler. Whiskered Bat.
The flight of this bat is very similar to that of the Pipistrelle;
and like that animal, it hawks under the shelter of a hedge or