Encyclopaedia Britannica > Volume 3, Anatomy-Astronomy

382 A It A C H
Aracli- posteriorly the vestige of rings or segments, forming a
nides. sorj; 0f dentation along the sides.
This rare species was discovered by M. Dufour in the
kingdom of Valentia. It inhabits rocks, and runs with
singular rapidity. It occurs both in Egypt and Syria.
Genus Philodromus, Walck.—Maxillae inclined upon
the languette, which is higher than broad. The eyes,
nearly equal in size, are disposed in the form of a cross
or semicircle. The mandibles are lengthened and
cylindrical.
Sp. Tigrina.—Thorax very broad, flattened, of a red¬
dish fawn-colour, brown laterally and posteriorly, white
in front. The pentagonal abdomen variously coloured by
means of minute red, brown, and white hairs, by which
it is covered. It is bordered with brown along the sides,
and is marked on the dorsal region with from four to six
impressed points. The belly is whitish. The legs are
long, slender, reddish, with brown spots.
This species is common on trees. When touched it
immediately either runs off with great rapidity, or sud¬
denly drops to the ground. Its cocoon, of a beautiful
white colour, incloses about one hundred unagglutinated
eggs. It places them in the clefts of trees, and guards
them with great care.
Genus Thomisus, Walck.—Mandibles shorter than in
the preceding genus, wedge-shaped. Four posterior
feet, shorter than the others. The sexes frequently
differ in their size and colours.
Sp. Citreus.—Colour citron-yellow. The abdomen
large, broader behind; the back with two red spots. In¬
habits flowers. The female is common in Britain; the
male more rare, of a smaller size, brown, banded with
yellowish-green.
13. Erraticce.
The four preceding tribes are characterized by their
usually sedentary habits. The remainder of the Aran-
eides are of a more wandering disposition. This is in
proper accordance with their other capabilities; for, as
they cannot spin webs for the capture of their prey, they
are under the necessity of moving about from place to
place to extend the sphere of those exertions, the suc¬
cessful issue of which depends on agility as well as cun¬
ning. “ Such,” says Evelyn, “ I did frequently observe
at Rome, which, espying a fly at three or four yards dis¬
tance, upon the balcony where I stood, would not make
directly to her, but crawl under the rail, till, being arrived
to the antipodes, it would steal up, seldom missing its
aim ; but if it chanced to want anything of being perfect¬
ly opposite, would, at first peep, immediately slide down
again,—till, taking better notice, it would come the next
time exactly upon the fly’s back; but if this happened
not to be within a competent leap, then would this insect
move so softly, as the very shadow of the gnomon seem¬
ed not to be more imperceptible, unless the fly moved;
and then would the spider move also in the same propor¬
tion, keeping that just time with her motion, as if the
same soul had animated both these little bodies; and
whether it were forwards, backwards, or to either side,
without at all turning her body, like a well-managed
horse; but if the capricious fly took wing and pitched
upon another place behind our huntress, then would the
spider whirl its body so nimbly about, as nothing could
be imagined more swift; by which means she always kept
the head towards her prey, though, to appearance, as im-
NIDES.
movable as if it had been a nail driven into the wood, till Aracli
by that indiscernible progress (being arrived within the nides.
sphere of her reach) she made a fatal leap swift as light-
ning upon the fly, catching him in the pole, where she
never quitted hold till her belly was full, and then carried
the remainder home.”1
Though the species above alluded to, and others consti¬
tuting the ensuing tribes, spin no webs, they are yet pro¬
vided with a sufficiency of the necessary material to en¬
able them to construct cocoons for their eggs, and also
to throw out an occasional thread to break their fall when
leaping on a vertical surface.
The eyes of the erratic spiders are always eight in
number, and are grouped rather along than aci'oss the
thorax, forming a curvilinear triangle, or a truncated or
quadrilateral oval. One or two pair of eyes are generally
much larger than the others. The thorax is large, and
the legs robust.
Tribe V.—Citigrad^.
In this tribe the legs are generally fitted for running.
The maxillm are always straight, and rounded at their
extremities. The eyes are grouped in a curvilinear tri¬
angle, or in an oval or oblong figure, of which the anterior
side is much narrower than the thorax taken in its great¬
est breadth. The thorax itself is ovoid, narrower in front,
and somewhat ridged or keel-shaped in its longitudinal
centre.
The females for the most part keep close to their co¬
coons, which they carry about them, either suspended at
their extremities, or applied between the chest and the
base of the abdomen. They watch over their young for
some time after they are hatched.
Genus Oxyopus, Latr. Sphasus, Walck.—Eyes ranged
two and two on four transverse lines, of which the two
at the extremes are the shortest; they describe a kind
of oval figure, truncated at each end. The languette
is elongated, narrow at the base, dilated and rounded at
the extremity. The first pair of legs is the longest;
the fourth and second are nearly equal; the third is the
shortest.
Sp. Variegatus.—Body hairy and gray, variegated with
red and white. Legs pale reddish, spotted with brown;
the tibial spines elongate. Inhabits France.
Sp. Lineatus. (PI. XLVI. fig. 9.)—Abdomen elongated,
yellowish, with lengthened black spots on the sides, and a
"black longitudinal band beneath. This species forms its
web on low growing plants, but nestles among the leaves
of trees about the period of laying.
G enus Ctenus, Walck.—Eyes placed on three transverse
lines (2, 4, 2) forming a curvilinear triangle, reversed,
and truncated anteriorly. The languette is square and
almost isometric. The fourth pair of feet are the long¬
est ; the first pair are next in length; the third are the
shortest.
This genus, according to Latreille, was established for
the reception of a species found in Cayenne. Others,
possessed of the same generic characters, have been
found both in that colony and in Brazil, but their descrip¬
tions have not yet been made public.
Genus Dolomedes, Latr.—Eyes disposed on three trans¬
verse lines (4, 2, 2,) representing a quadrilateral figure,
somewhat broader than long. The two posterior are
1 Evelyn’s Travels in Italy.