ERIAUCHENUS WORKMANNI (from Cambridge).]

Epeira prompta, a variety of parvula, is a common spider in the State
of Wisconsin. It is most frequently seen on cedar bushes, where its
color harmonizes with that of the foliage and fruit. During the day it
usually rests on a branch near its web. The back of the abdomen is of
a peculiar bluish-green, exactly like that of the lichens growing on
tree trunks. The bluish color is broken by waving black lines which
imitate the curling edges of the lichens. The one represented in the
plate was found on an old cedar which was covered with lichens. It was
kept for two weeks in a glass-covered box, where it spent most of the
time crouching in a corner. It built no web, but spun some irregular
lines to run about on. It ate gnats, flies, and once a little jumping
spider, S. pulex, which we were keeping in the same box, leaping upon
its prey, as noted by Hentz, like an Attus. This seems a curious habit
to be acquired by an Epeirid, since spiders, as we have noticed among
our captives, are usually dependent for food upon what is caught in
their webs. Prompta moves awkwardly, but very rapidly.

Drapetisca socialis, while quite a different looking spider, is
protected in the same way--by its resemblance to the bark upon which
it lives. Emerton speaks of finding it on the bark of spruce trees,
which it "closely resembles in color." Menge says that it is common
in Prussia, where it is seen in great numbers on fir trees, whose
spotted bark it resembles in color, so that it is not easily seen. We
have found them, most commonly, upon birch trees, and in this
situation their color adaptation is perfect. Both the spider and the
peeling bark of the tree are of a light silvery brown, covered with
little blackish marks. On the bark these marks are, of course,
irregular, while on the spider they form a pattern made up of straight
and curved lines and dots, the legs being silvery, barred with
blackish.

Another little Theridion that is found on birch bark has the same
colors arranged a little differently. The abdomen above has a large
and peculiarly irregular black patch, which shades off into mottled
brown and black on the sides and below. The cephalothorax has stripes
of brown and black, and the legs are barred with light and dark brown.

Spiders that live upon walls, fences, tree trunks, or on the ground
harmonize in color with the surfaces upon which they are found, being
usually gray, brown or