Encyclopaedia Britannica > Volume 3, Anatomy-Astronomy

380 A R A C H
Arach- middle of her spinners, and which is so elastic that it is
nides. capable of great expansion and contraction; and if a hole be
made in it, it immediately closes again. Next she spreads
over her belly a pellicle of the same material, and ascends to
the surface. The precise mode in which she transfers a
bubble of air beneath this pellicle is not accurately known ;
but from an observation made by the ingenious author of
the little work from which this account is abstracted, he
concludes that she draws the air into her body by the
anus, which she presents to the surface of the pool, and
then pumps it out from an opening at the base of the
belly, between the pellicle and that part of the body, the
hairs of which keep it extended. Clothed with this aerial
mantle, which to the spectator seems formed of resplen¬
dent quicksilver, she plunges to the bottom, and, with as
much dexterity as a chemist transfers gas with a gas¬
holder, introduces her bubble of air beneath the roof pre¬
pared for its reception. This manoeuvre she repeats ten
or twelve times, until at length, in about a quarter of an
hour, she has transported as much air as suffices to ex¬
pand her apartment to its intended extent, and now finds
herself in possession of a little aerial edifice—I had
almost said an enchanted palace—affording her a com¬
modious and dry retreat in the very midst of the water.
Here she reposes unmoved by the storms that agitate
the surface of the pool, and devours her prey at ease and
in safety. Both sexes form these lodgings. At a parti¬
cular season of the year the male quits his apartment,
approaches that of the female, enters it, and enlarging it
by the bubble of air that he carries with him, it becomes
a common abode for the happy pair.1 The spider which
forms these singular habitations is one of the largest Eu¬
ropean species, and in some countries not uncommon in
stagnant pools.”2
Tribe II.—IxiEQUiTELiE.
External spinners conical, convergent, slightly project¬
ing, disposed en rosette. Legs slender, first and last pair
usually the longest. The maxillae are inclined on the
tongue, and are either narrow or present no sensible
enlargement at their superior extremity. The abdomen
is more voluminous, softer, and more highly coloured
than in the preceding tribe. Their webs constitute an
irregular net-work of various forms, the threads of which
cross each other in different directions. They bind their
prey with cords, which, though silken, secure them very
effectually. The species are short-lived, and tend their
eggs very carefully till the exclusion of the young.
Genus Scytodes, Latr.—Eyes six, disposed in pairs.
M. Dufour states that the crotchets of the tarsi are in¬
serted in a supplementary article.
Sp. Thoracica. (PI. XL VI. fig. 6.)—Pale reddish-white,
spotted with black. Thorax large, somewhat orbicular.
Abdomen not globose.
This species inhabits houses. It has been found near
Dover, but is otherwise scarcely known as a British spe¬
cies.
Genus Theridion, Walck.—Eyes eight in number, of
which four in the centre form a square, the two ante¬
rior being placed upon a small eminence, and a pair are
placed on each side upon a common elevation. The
thorax is almost triangular, or shaped like a heart re¬
versed.
N I D E S.
Sp. Malmignatto. Aranea \3-guttata, Fab.—Lateral Arad,
eyes, separated from each other. Body black, with thir- aides,
teen small round spots of a blood-red colour on the abdo-
men. This species inhabits Corsica, the inhabitants of
which island hold it in great dread, from the belief that
its bite is dangerous, if not mortal.
Another species, the Theridion henignum of Walck-
enaer, may from its name be presumed to possess ano¬
ther character. It lives in autumn among the clusters
of grapes, where it watches for its prey, and thus deters
many insects from injuring the fruit. The prejudice
against this genus probably arises from several of them
being of a dark colour, with red spots resembling drops of
blood upon their bodies.
Genus Episinus, Walck.—Eyes eight, near each other,
and placed upon a common elevation. The thorax nar¬
row and almost cylindrical.
Sp. Truncatus.—Thorax acute in front, rather longer
than broad, obscure brown above, reddish brown beneath.
Abdomen pyramidal, truncated behind, its anterior por¬
tion brown, third pair of legs whitish, the others brown.
Genus Pholcus, Walck.—Eyes eight, tuberculated, di¬
vided into three groups, of which there is one on each
side composed of three eyes disposed in a triangle, and
a third in the centre, somewhat advanced, composed of
two eyes on a transverse line.
Sp. Phalangioides, Walck. Araignee domestique d
longues pattes, Geoff.—Body long, narrow, pubescent, of
a livid or pale yellow colour. The abdomen is almost cy¬
lindrical, very soft, and spotted above with black. The
legs are very long and slender, with whitish rings at the
extremities of the thighs and tibiae.
This species is common in houses in the western parts
of England. Its body vibrates like that of some tipula1.
The female carries her eggs in an agglutinated mass be¬
tween her mandibles.
Tribe III.—Orbitel^e.
In this tribe the exterior spinners and the legs re¬
semble those of the preceding, but the maxillae differ,
being straight, and sensibly broader at their extremity.
The first and second pair of legs are the longest. The
eyes are eight in number, of which four are placed quad-
rangularly in the centre, and a pair on each side. These
spiders differ from the Incequitelce in the form of their
webs, which are composed of a regular net-work, formed
of concentric circles, crossed by straight lines or radii,
proceeding from the centre, where the animal lies, to the
circumference. Some conceal themselves in cavities, or
in chambers built by themselves, near the margins of
their webs, which are sometimes horizontal, sometimes
perpendicular. Their eyes are numerous, agglutinated,
and inclosed in a large cocoon.
Genus Linyphia, Lati\—Four central eyes, of which the
posterior pair are larger, and separated by a larger
space ; the others are in pairs, one on each side, and
placed obliquely. The maxillae are enlarged at their
superior extremity.
This genus constructs among brooms and other bushes
a slender, open, horizontal net, from which various threads
proceed irregularly upwards to different points.
1 Mcmoire pour servir d commencer PHistoire des Araignees Aquatiques.
* Introduction to Entomology, by Kirby and Spence, vol. i. p. 4011.