hich of these advantages has directed the development of
mimetic tendencies among spiders.

While among beetles and butterflies we most commonly find mimicry of
one species by another within the same order, we have no instance of a
spider mimicking another spider. This may be accounted for by the fact
that the specially protected spiders depend for their safety upon the
possession of hard plates and spinous processes, and although the
hardened epidermis might be imitated (we know that hard-shelled
beetles are mimicked by others that are soft), spines could scarcely
be imitated by a soft-bodied creature with sufficient accuracy to
insure disguise.

While spiders most commonly mimic ants, we hear also of their
imitating beetles, snail-shells, ichneumons and horseflies. There is
also a curious Madagascar species which looks exactly like a little
scorpion, the resemblance being heightened by its habit of curving its
flexible tail up over its back when irritated.

Those that resemble beetles comprise nearly all the species of the
genera Coccorchestes and Homalattus. These are small spiders with
short, convex bodies. The abdomen fits closely over the cephalothorax,
and the epidermis, which has usually a metallic lustre, is sometimes
coriaceous. Striking examples are found in H. coccinelloides, which
bears a strong resemblance to beetles of the family Coccinelloidae, and
in C. cupreus, in which certain marks on the abdomen imitate the
elytra of beetles.

The following account of a spider which mimics a snail-shell is given
by Mr. G. F. Atkinson;--

"An undescribed species of _Cyrtarachne_ mimics a snail-shell, the
inhabitant of which, during the summer and fall, is very abundant on
the leaves of plants in this place. In the species of Cyrtarachne the
abdomen partly covers the cephalothorax, is very broad at the base, in
this species broader than the length of the spider, and rounds off at
the apex. When it rests upon the under side of a leaf with its legs
retracted it strongly resembles one of these snail-shells by the color
and shape of its abdomen. The two specimens which I collected deceived
me at first, but a few threads of silk led me to make the examination.
The spider seemed so confident of its protection that it would not
move when I jarred the plant, striking it several hard blows. I
pulled the spider forcibly from the leaf, and it did not exhibit any
signs of movement until transferred to the cyanide bottle." .