WALCKENAERA. 
305 
■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. 
Walckenaera exilis. PI. XXI, fig. 220. 
Walckenaera exilis, Blackw., Annals and Mag. of Nat. Hist., second series, vol. xi, 
p. 24. 
— — Blackw., Ibid., p. 120. 
Length of the male, #h of an inch; length of the cephalo-thorax, 4 th, breadth, Ath; 
breadth of the abdomen, 4th; length of an anterior leg, ith; 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 oval, 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 of 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 daik- 
brown tint; 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, pro¬ 
jecting over the base of the cephalo-thorax; it is of a yellowish-brown colour, with obscuie 
marks of a deeper shade. 
A specimen of this diminutive Walckenaera, 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. 
