632 Mr. BuackwaLr’s Descriptions of new Species of Spiders. 
ais; breadth of abdomen ; length of an anterior leg Pr; length of a 
leg of the third pair 20. 
Cephalo-thorax oval, glossy, depressed on the sides, which are marked with 
slight furrows diverging from the upper part towards the margins; in 
the medial line of the posterior region there is an indentation. Mandi- 
bles conical, armed with teeth on the inner surface, and inclined towards 
the sternum, which is broad and heart-shaped. Maxillæ inclined towards 
the lip, which is semicircular and prominent at the extremity. First and 
fourth pairs of legs the longest, and equal in length, third pair the 
shortest. Anterior intermediate eyes the smallest of the eight. The tarsi 
of this spider, and of all the species belonging to the genus which have 
come under my observation, are terminated by three claws; the two 
superior ones curved and pectinated, and the inferior one inflected near 
its base. Abdomen thinly clad with hairs, glossy, convex above, project- 
ing over the base of the cephalo-thorax. This species is black, with the 
exception of the mandibles, maxillæ, legs, and palpi, which are brown, 
the first two being much the darkest. | 
The male is rather smaller than the female, but resembles her in colour, 
and in the relative length of his legs. The anterior part of the cephalo- 
thorax, where the eyes are situated, is elevated, but obtuse, with an oblong 
indentation on each side, extending backwards from the lateral eyes. 
Third and fourth joints of the palpi short, the latter being much the 
stronger; fifth joint oval, convex and hairy externally, concave within, 
comprising the palpal organs, which are highly developed, complicated 
in structure, with a very prominent, filiform, curved, black spine, enve- 
loped in a delicate membrane, originating about the middle of the outer 
side, and a short, straight, pointed one at their extremity ; they are of a 
reddish brown colour. 
Both sexes of Walckenaéra atra, the males having the palpal organs fully 
developed, were found in May 1838, under stones in moist pastures near 
Llanrwst. The species probably comes near Theridion acuminatum, Wider, in 
Mus. Senk. i. p. 232. t. 15. f. 11. | 
19. Walckenaéra hiémalis. Cephalo-thorace mandibulis maxillis labio ster- | 
