and the legs the lightest coloured. The two superior tarsal claws are curved and pectinated,
and the inferior one is inflected near its base. The cubital and radial joints of the palpi are
short, the latter being much the stronger; the digital joint is oval, with a projection on the
outer s i d e i t is convex and hairy externally, concave within, comprising the palpal organs,
which are highly developed, complicated in structure, with a slender process at the base,
directed upwards, a bold protuberance on the inner side, and a fine, convoluted, filiform spine,
enveloped in membrane, extending from the upper part to the extremity j their colour is red-
brown. The abdomen is oviform, thinly clothed with hairs, convex above, projecting over
the base of the cephalo-thorax j it is of a brownish-black colour, and that of the branchial
opercula is pale-yellow.
M. Walckenaer is of opinion that Wdckenaera bicolor should rank as a synonym of Argus
elongatus (Hist. Nat. des Insect. Apt., t. iv, p. 509); but they may be readily distinguished
from each other by differences in size, structure, and colour.
Males of this species, with the palpal organs fully developed, were taken in July, 1836,
on rails near Llanrwst.
Walckenaëra parva. PI. XXI, fig. 219.
Walckenaëra parva, Blackw. Linn. Trans., vol. xviii, p. 635.
Blackw., Annals and Mag. of Nat. Hist., second series, vol. ix,
p. 465.
Argus parvus, Walck., Hist. Nat. des Insect. Apt., tom. iv, p. 508.
Length of the female, ^th of an inch ; length of the cephalo-thorax, ^nd, breadth, ^th ;
breadth of the abdomen, ^th ; length of an anterior leg, ^th ; length of a leg of the third
pair, 53th.
The cephalo-thorax is oval, glossy, very convex behind the eyes, depressed in the
posterior region, with an exceedingly minute indentation in the medial line ; the falces are
moderately powerful, conical, armed with teeth on the inner surface, and inclined towards the
sternum, which is heart-shaped and glossy ; the maxillae are strong, and inclined towards the
lip, which is semicircular and prominent at the apex.- These parts, with the legs and palpi,
are of a brown colour, the falces, lip, and margins of the cephalo-thorax being the darkest.
The two superior tarsal claws are curved and pectinated, and the inferior one is inflected near
its base. The abdomen is oviform, convex above, projecting over the base of the cephalo-
thorax ; it is thinly clothed with hairs, glossy, and of a very dark, brown-black hue, that of
the branchial opercula being brown.
The male, though smaller than the female, resembles her in colour ; but it differs from
her in having an indentation on each side of the anterior part of the cephalo-thorax, immediately
behind the lateral eyes. The radial joint of the palpi, which is rather shorter and
stronger than the cubital, projects an acute, prominent apophysis from its extremity, in front ;
t he digital joint is oval, convex and hairy externally, concave within, comprising the palpal organs,
which are moderately developed, not complicated in structure, somewhat prominent, and of a
red-brown colour.
In December, 1836, and January, 1837, this minute spider was seen in considerable
numbers on rails near Llanrwst.
W alck en a er a e x il i s . PI. XXI, fig. 220.
WalcJcenaera exilis, Blackw., Annals and Mag. of Nat. Hist., second series, vol. xi,
p. 24.
— — Blackw., Ibid., p. 120.
Length of the male, A*h of an inch; length of the cephalo-thorax, Ath, breadth, Ath;
breadth of the abdomen, Ath; length of an anterior leg, A * ; length of a leg of the third
pair, ^th.
The eyes are seated on black spots; the four intermediate ones describe a narrow,
oblong trapezoid, whose anterior side is the shortest, and those of each lateral pair are placed
obliquely on a small tubercle and are contiguous; the lateral eyes are the largest, and the
two anterior ones of the trapezoid are much the smallest of the eight. The cephalo-thorax
is oyal, convex, glossy, prominent before, depressed in the posterior region, with a narrow
indentation directed backwards from each lateral pair of eyes, and is of a dark-brown colour.
The falces are small, conical, armed with teeth on the inner surface, and inclined towards the
sternum, which is heart-shaped; the maxillae are enlarged where the palpi are inserted, and
inclined towards the lip, which is semicircular and prominent at the apex; the legs are
moderately long and hairy; the two superior tarsal claws are curved and pectinated, and the
inferior one is inflected near its base. These parts are o f a pale-brown hue, the falces and
lip being the darkest, and the sternum having a slight tinge of green. The palpi resemble
the legs in colour, with the exception of the radial and digital joints, which have a dark-
brown t in t; the radial is stronger than the cubital joint, and projects two pointed apophyses
from its extremity, in front; the digital joint is oval', convex and hairy externally, concave
within, comprising the palpal organs, which are highly developed, very prominent, complicated
in structure, with a short, curved, black, projecting spine at their extremity, and are of a
brown colour, tinged with red. The abdomen is small, oviform, hairy, convex above, projecting
over the base of the cephalo-thorax; it is of a yellowish-brown colour, with obscure
marks of a deeper shade.
A specimen of this diminutive Wakhenaera, in a state of maturity, was discovered among
moss growing at the root of an oak in a wood on the northern slope of Gallt y Rhyg in
October, 1852.