632 Mr. Blackw all's Descriptions of new Species of Spiders. 



■^ ; breadth of abdomen -^ ; length of an anterior leg ^ ; length of a 

 leg of the third pair ■^. 

 Cephaio-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. Maxillae 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 cephaio-thorax. This species is black, with the 

 exception of the mandibles, maxillae, 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 cephaio- 

 thorax, whei-e 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 IValchenaera 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. fValckenaera hiemalis. Cephalo-thorace mandibulis maxillis labio ster- 



