ThERIDION R1PARIUM. PI. XIII, fig. 115.
Theridion riparium, Blackw., Research, in Zool., p. 354.
— — Blackw., Annals and Mag. of Nat. Hist., second series, vol. viii,
p. 338.
— saxatile, Walck., Hist. Nat. des Insect. Apt., tom. ii, p. 328.
Theridium — Koch, Uebers. des Arachn. Syst., erstes Heft, p. 8.
— — Koch, Die Arachn., Band iv, p. 116, tab. 141, figs. 324, 325.
Length of the female, *th of an inch; length of the cephalo-thorax, ^th, breadth, ^ th;
breadth of the abdomen, ^ th; length of an anterior leg, ^ths; length of a leg of the third
pair, Aths.
In form and colour this species bears a close resemblance to Theridion Sisyphum, but may
be distinguished from it by its smaller size and different economy. The cephalo-thorax is
convex, glossy, slightly compressed before, rounded on the sides, and has a large indentation
in the medial line; the falces are small, conical, and vertical; the maxillae are inclined towards
the lip, which is quadrate; the sternum is heart-shaped, and the palpi are short and robust.
These parts are of a red-brown hue, the cephalo-thorax and sternum being much the darkest.
The legs are moderately long and of a yellowish-brown colour, with broad, red-brown annuli.
The four intermediate eyes form a square, the two anterior ones being seated on a protuberance
; those constituting each lateral pair are placed obliquely on a small tubercle, and are
contiguous. The abdomen is thinly clothed with hairs, pointed at the spinners, very convex
above, and projects over the base of the cephalo-thorax; the upper part is of a red-brown
colour, mottled with black and white, and bisected by an irregular, transverse, white line,
interrupted in the middle by a triangular black spot, between which and the spinners there is
a curved, transverse, black lin e ; the under part, which has a brownish-black tint, is marked
with a transverse band of red-brown near the spinners; and the colour of the branchial
opercula is red-brown.
The male is much smaller,, darker coloured, and less distinctly marked than the female,
but the relative length of its legs is the same. The cubital and radial joints of its palpi are
short; the digital joint is somewhat oval, with a pointed process at its base, which falls into
a notch in the radial joint and extends to its articulation with the cubital jo int; it is convex
and hairy externally, concave within, comprising the palpal organs, which are highly developed,
not very complicated in structure, and are of a red-brown colour. The convex sides of
the digital joints are directed towards each other.
The economy of this species, which is evidently identical with the Theridium saxatile of
M. Koch, is very remarkable. It spins under the projections of broken, precipitous banks in
the woods about Oakland a snare composed of fine, glossy lines, arranged after the manner of
the Theridia. The union of the sexes takes place in July, and in August the female fabricates
a slender, conical tube of silk, of a very slight texture, measuring from one and a half to two
and a half inches in length, and about half an inch in diameter at its lower extremity; it is
closed above, open below, thickly covered externally with particles of indurated earth, small
stones, and withered leaves and flowers, which are incorporated with it, and is suspended
perpendicularly in the snare by lines attached to its sides and apex. In the upper part of
this singular domicile the female constructs several globular cocoons of yellowish-white silk, of
a slight texture, having'a mean diameter of about one eighth of an inch, in each of which she
deposits from twenty to sixty small spherical eggs of a pale, yellowish-white colour, not
agglutinated together. The young, after quitting the cocoons, remain a long time with the
female, and are supplied by her with food, which consists chiefly of ants.
Theridion nervosum. PI. XIII, fig. 116.
Theridion nervosum, Walck., Hist- Nat. des Insect. Apt., tom. ii, p. 301.
‘villi. Hahn, Die Arachn., Band ii, p. 48, tab. 58, fig. 133.
_ __ Blackw., Annals and Mag. of Nat. Hist., second series, vol. viii,
p. 44*.
1 — Sisyphus, Sund., Vet. Acad. Handl., 1831, p. 115.
Theridium " — * Koch, TTebers. des Arachn. Syst., erstes Heft, p. 8.
— Koch, Die Arachn., Band viii, p. 73, tab. 273, fig. 644.
Titvlus 13, Lister, Hi^K 'Animal. Angl. De Aran., p. 51, tab. 1, fig. 13.
Length of the female, jth of an inch ; length of the cephalo-thorax, nth, breadth, ^th ;
breadth of the abdomen, nth ; length of an anterior leg, «ths ; length of a leg of the third
pair, nths.
The four intermediate eyes form a square, the two anterior ones, which are the darkest
and rather the largest of the eight, being seated on a protuberançfHthose constituting each
lateral pair are placed obliquely on a small tubercle and are nearly in jgjpntact. The cephalo-
thorax is convex, glossy, slightly compressed before, rounded on the sides, and has a large
indentation in the medialline; it is of a dull-yellow colour, with dark, reddish-brown lateral
margins, and a broad band of the same hue extending along the middle. The falces are
conical, vertical, and have a ÿellowish-brown tint. The maxillæ are convex at the base,
strongly inclined towards the lip, and of a pale, red-brown colour. The lip is semicircular,
and has a brownish hue. The sternum «heart-shaped, and of a dull-yellow colour, with
narrow, pale, red-brown margins. The legs are .moderately long, provided with hairs, and
have a yellowish-brown tint, with pale, red-brown annuli at the joints ; the first pair is the
longest, then the fourth, and the third pair is the shortest; the two superior tarsal claws are
curved and pectinated, and the inferior one is inflected near its base. The palpi are short,
of a yellowish-brown colour, and are terminated by a curved, pectinated claw. The abdomen
is glossy, thinly clothed with hairs, subglobose, pointed at the spinners, and projects over the
base of the cephalo-thorax; in the medial line of the upper part there is a broad, pale, red-
brown band, which is thickly spotted with white anteriorly, and comprises a longitudinal,
yellowish-white line situated above the anus ; this band is bounded on each side by a broad,