Pholcus phalangioides. PI. XV, fig. 137.
Pholcus phalangioides, Walck., Hist. Nat. des Insect. Apt., tom. i, p. 652. .
— — Latr., Gen. Crust, et Insect., tom. i, p. 99.
— — Hahn, Die Arachn., Band ii, p. 34, tab. 50, fig. 119.
— . — Koch, Uebers. des Arachn. Syst., erstes Heft, p. 20.
. — — Blackw., Linn. Trans., vol. xix, p. 125.
— — Blackw., Annals and Mag. of Nat. History, second series,
vol. viii, p. 447.
— opilionoides, Koch, Die Arachn., Band iv, p. 95, tab. 135, fig. 311.
Length of the female, §rd of an inch; length of the cephalo-thorax, ^th, breadth, ^ th ;
breadth of the abdomen, Jth; length of an anterior leg, 2^ th; length of a leg of the third
pair, l^th.
The cephalo-thorax is circular, slightly convex, glossy, with some long hairs in the
medial line, but without the customary indentation; the anterior part, on which the eyes are
situated, is prominent, and the space between those organs and the falces is broad and
vertical; it is of a pale yellowish-brown colour, a brown band, the posterior part of which is
the broadest, extending along the middle. The eyes are seated on black Spots, the two
placed transversely between those constituting the lateral triangles being much the smallest
of the eight. The falces are small, vertical, united at the base, somewhat cuneiform, and
armed with a short* slightly curved fang, and a single, strong tooth on the inner side, at the
extremity; the maxillae are enlarged at the base, where the palpi are inserted, and inclined
towards the lip, which is short, broad, contracted at the base, dilated in the middle, and
rounded at the apex; the sternum is heart-shaped. These parts are of a yellowish-brown
colour, the falces and maxillae being darkest at their extremities. The legs are very long and
slender, and are provided with short, fine hairs; they have a pale-brown hue, the colour of
the extremities of the femora and tibiae being light yellowish-brown, and that of the genual
joint dark-brown; the first pair is the longest, then the second, which a little surpasses the
fourth pair, and the third pair is the shortest; each tarsus is terminated by three claws; the
two superior ones are curved and deeply pectinated, and the inferior one is inflected near its
base. The palpi are short, and have a yellowish-brown tint. The abdomen is somewhat
cylindrical, being rather larger at the posterior than at the anterior extremity ; it is soft,
thinly clothed with hairs, and of a pale yellowish-brown colour, with an irregular band of a
darker hue extending along the middle of the upper part, and some obscure, dark spots on
the sides; the spinners are of a yellowish-brown colour marked with dark-brown, and are
situated under the extremity of the abdomen; the sexual organs have a red-brown tint; they
are prominent, and have a small, cylindrical process in connexion with them, which is directed
backwards.
The male greatly resembles the female, but its. abdomen is slenderer, and the dark,
longitudinal band on the upper part is less perfectly defined. Its falces have a small, dark,
conical process near their extremity, in front, at the base of which, on the inner side, there
is a slender, pointed projection; and another small, conical process, of a lighter colour,
occurs at their base, towards the outer side. The axillary joint of the palpi has a large
apophysis underneath, projecting from it at right angles, on the base of which there is a
pointed protuberance; the humeral joint is gibbous on the under sid e ; the radial joint is
greatly dilated, and is much larger than the cubital jo int; the digital joint is small, nearly
circular, convex and hairy externally, and slightly concave on the under side, with which
concavity the palpal- organs are connected; they are very highly developed and complicated
in structure, consisting of two parts; one, directed downwards, has a bold protuberance
underneath, and is enlarged, but depressed, at its extremity, which is provided with several
small points; it is of a red-brown colour, the outer side, which is fringed with long hairs,
being the palest; the other part, situated near the insertion of the former, is attached to the
digital joint by a dark, protuberant base; it is greatly dilated, nearly globular, of a pale
flesh-colour, bisected by a fine red line, and projects upwards a strong, curved, compressed
process, slightly serrated on its outer edge, and having two prominences at its base, one on
the outside of the curve and the other within it, the extremity of the latter being bent
backwards; the colour of this part and its appendages is dark reddish-brown, and behind
them there is a pale, membraneous process, directed upwards, whose extremity appears
between the strong, curved process and the prominence at its base, on the inner side.
In the month of June, the female of this species deposits her eggs in a globular cocoon of
a very slight texture, which she carries with her wherever she moves, holding it with the falces.
Adult and immature individuals of both sexes have been received from Barmouth, in
Merionethshire, from Liverpool, and from the Isle of Wight.
The spider referred to by Mr. Jesse in his ' Scenes and Tales of Country Life,’ pp. 202,
203, as remarkable for the rapidity of its vibratory motions when disturbed, most probably is
Pholcus phalangioides, which frequents ancient buildings in the south of England, and like
JEpeira diadenia, Theridion quadripunctatum, and some other species, has the habit of violently
agitating itself when anything suddenly touches its lines. That this vibratory motion,
which in the case of Pholcus phalangioides appears to acquire its maximum velocity, is produced
by the partial contraction and extension of the joints of the legs in quick succession,
may be ascertained by occasioning specimens of JEpeira diadema to continue the action till it
becomes so slow, in consequence of the fatigue experienced by the animals, that there is no
difficulty in determining the manner in which it is effected. This singular proceeding is
evidently intended by the spider to communicate motion to its snare, and thus to cause the
struggles of any insect entangled in it, by which means it is directed with certainty to its
victim.