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Trimen gives an account of the imitation, by spiders, of horseflies, a
case falling into Class 2, as follows:--

"Hunting spiders are in some cases very like their prey, as may
everywhere be noticed in the case of the species of Salticus which
catch horseflies on sunny walls and fences. The likeness is not in
itself more than a general one of size, form and coloring; but its
effect is greatly aided by the actions of the spider, which walks
hurriedly for short distances, stopping abruptly, and rapidly moving
its falces, in evident mimicry of the well-known movements so
characteristic of flies."

Instances of spiders mimicking ants are very numerous, and in many
cases the resemblance is so close as to, at first sight, deceive a
trained naturalist. This resemblance is brought about by the spider's
body being elongated and strongly constricted, so that it appears to
be composed of three segments instead of two, by the color, by the way
in which the spider moves about, zig-zagging from side to side like an
ant, and by its habit of holding up one pair of its legs and moving
them in such a way that they look exactly like the antennae of an ant.

Ants may be regarded as specially protected, by their sharp, acid
flavor, and in some species by the possession of stings or of horny
processes.

On the ground that there are birds which do eat ants, and eat them
greedily, it has been thought by some naturalists that they cannot be
considered specially protected creatures, and that, as spiders can
therefore derive no protection from mimicking them, all cases of such
mimicry depend upon the spider's increased ability to capture the ants
as prey, but I am convinced that this is too hasty a conclusion. It is
unquestionably true that some birds feed almost exclusively upon ants,
but these are the exceptions. It is a common thing to find that
specially protected groups, which are safe from the attacks of most
creatures, have their special enemies. Thus, even the nauseous
Heliconidae are preyed upon by certain spiders and wasps; and bees, in
spite of their stings, are preferred to other insects by the
bee-eaters. Moreover, the ant-devouring birds are found largely among
the wood-peckers, which eat the ants that run on the trunks of trees,
and are therefore not a source of danger to the ant-like spiders, the
American species of which, so far as I can learn, live entirely upon
the ground.

In the United States comparatively small n