[Illustration: FIG. 359. Web of Erigone dentigera among stems of grass
close to the ground. About the real size.]
The Erigones are all very small spiders, and for this reason few of them
will be described. They live, for the most part, near the ground in
grass, moss, and dead leaves, with small webs like those of Linyphia,
and are seldom seen unless carefully searched for. There is one season
of the year, however, when the Erigones appear in immense numbers. This
is during the fine weather that comes after the first frosts in October
and November, when they, in company with the young of many larger kinds
of spiders, come to the tops of posts and fences and, turning their
spinnerets upward, allow threads to be drawn out by ascending currents
of air, until sometimes the spiders are lifted off their feet and
carried long distances. Though not so easily seen, the same performance
is going on at the tops of grass and bushes, and at times the whole
country is covered with threads of silk, and the threads in the air
tangle together into flakes, which at length fall, sometimes from great
heights. This appearance is called in England "gossamer" and in Germany
the "flying summer" and the "old woman's summer." Why the spiders spin
the thread and what use it is to them to be blown about are unknown. At
the time of the autumn flights great numbers of these spiders may be
seen on fences and doorsteps in city streets wherever there is a
neighboring park or grass plat, and the spiders probably live the rest
of the year among this grass near the ground.
[Illustration: FIG. 360. Erigone dentigera trying to fly. Enlarged eight
times. From a photograph on Boston Common.]
[Illustration: FIGS. 361, 362, 363, 364, 365. Erigone dentigera.--361,
side of male. 362, back of cephalothorax of male enlarged sixteen times.
363, female. 364, mandible of male. 365, maxilla of male.]
$Erigone longipalpis$ and $dentigera.$--These spiders are a tenth of an
inch to a twentieth of an inch long and generally dark brown in color,
with the cephalothorax smooth and shining. In some, especially the
larger males, the cephalothorax is bright orange and the legs partly of
the same color. The females vary considerably in size, but are otherwise
much alike. The peculiarities are in the males. The head is about half
the length of the cephalothorax and abruptly raised and rounded on the
top (fig. 361). Along the sides of the thorax are small pointed teeth of
various sizes in a single irregular row (fig. 362). The mandibles are
very much thickened in the middle and have a row of teeth on the front
outer side (fig. 364). The palpi of the males are sometimes as long as
the whole body and of a complicated shape. The femur is curved upward
and forward and has a row of little teeth on the under side. The patella
and tibia are together about as long as the femur. The patella has at
the end a straight tooth directed downward with a short point (fig.
361). The tibia is widened at the end, where it spreads around the base
of the tarsus. The maxillæ are much thickened and the bases of the palpi
spread wide apart (fig. 365). The palpi are usually carried doubled up
in front of the head, with the curved ends of the femora just below the
eyes and the palpal organs over the ends of the mandibles. The legs of
Erigone are only moderately long, and they walk easily, like the small
Drassidæ. They move slowly and are not easily frightened, so that at the
time of flying they can be closely watched.
[Illustration: FIGS. 366, 367. Erigone autumnalis.--366, under side of
cephalothorax of male. 367, palpus of male.]
$Erigone autumnalis.$--This is one of the few species of Erigone that
can be distinctly separated from the others. It lives in the same places
and is found with _longipalpis_ in the autumn flights. It is only a
twentieth of an inch long, but can be distinguished by its light color
and bright yellow head. The palpi of the males have the tibia shorter
than the patella and the tooth on the patella turned more forward than
in _longipalpis_, with a longer and sharper point tapering from the base
to the tip (fig. 367).
[Illustration: FIGS. 368, 369, 370. Ceratinella lætabilis.--368, outline
of side of female enlarged sixteen times. 369, 370, end of male palpus.]
$Ceratinella lætabilis.$--This is about the same size as _fissiceps_,--a
sixteenth of an inch long,--but much darker colored, and the males do
not have horns or humps on the head. The cephalothorax and sternum are
dark brown, and the legs dark orange. The thickened circle on the
abdomen (fig. 368) is dark orange brown and the thinner parts gray. In
the female the thick circle is usually wanting and the whole abdomen
dark gray, with lighter spots around the muscular marks. There are also
hardened spots around the stem of the abdomen and under the spinnerets
in both sexes. The head is slightly elevated behind the eyes, a little
more in the male than in the female. The male palpi (figs. 369, 370)
are shorter and stouter than those of _fissiceps_. It lives in dead
leaves and moss, sometimes under stones, and is sometimes found flying
in the autumn.
[Illustration: FIGS. 371, 372, 373. Ceratinella fissiceps.--371,
varieties in the form of the head. 372, 373, palpus of male.]
$Ceratinella fissiceps.$--These little spiders are among the smallest
species, measuring only a sixteenth of an inch in length. The
cephalothorax and abdomen are short and round, and the abdomen has a
round thickened spot on the back, more deeply orange colored than the
part around it. The head is black around the eyes, and a black line
extends backward half the length of the cephalothorax. The head of the
male extends forward over the mandibles, carrying with it the front
middle eyes, and above it is a rounded hump with the hind middle eyes.
The pairs of lateral eyes are opposite the crease between the humps
(figs. 371). The female has at the same point a slight crease across the
head and an elevation before and behind it. They are very common on low
bushes in summer and under leaves in winter, and are occasionally seen
in the autumn flights.
[Illustration: FIGS. 374, 375, 376. Cornicularia directa.--374, male
enlarged sixteen times. 375, head of male showing the double horn. 376,
head of male from above.]
$Cornicularia directa.$--The males and females are of the same size and
about a twelfth of an inch long. The cephalothorax is brown, varying in
different individuals. The abdomen is gray, with the muscular spots
lighter than the rest. The cephalothorax is long, narrowing gradually
toward the head. In the males there is a slender horn extending forward
between the eyes, a little thickened at the end and covered on the upper
side with stiff hairs in rows (fig. 376). Under this horn is a smaller
one about half as long and close against it (fig. 375). In females the
horns are absent, but the shape of the head and arrangement of the eyes
are the same, except that the eyes are closer together. There are
several other species of Cornicularia, some with similar horns and
others with single horns on the heads of the males. They are found under
leaves in winter, on plants and fences, and among the flying spiders in
autumn.
[Illustration: FIGS. 377, 378. Ceratinopsis interpres.--377, head of
male. 378, end of palpus of male.]
$Ceratinopsis interpres.$--Length about a tenth of an inch. Color bright
orange, with a little black around the eyes and the spinnerets. In the
female the height of the head equals the length of the mandibles, and in
males it is greater. The size of the sexes is about the same. The upper
middle eyes are a little larger and farther apart than the front middle
pair, and between them is a flattened space covered with stiff black
hairs, longer in the male than in the female (fig. 377). The male palpi
have the femur as thick as the femur of the first leg and the tibia very
short and wide, with a little recurved point on the front edge. They
live on low bushes in summer and under leaves in winter.