Mr. J. Blackball on new Species of Spiders. 445 



Family Linyphiid/b. 

 Genus Walckenaera, Blackw. 

 Walckenaera pratensis. 



Length of the female £th of an inch ; length of the ccphalo- 

 thorax j^tii, breadth ^ n th ; breadth of the abdomen j^th ; 

 length of a posterior leg ^th ; length of a leg of the third 

 pair J th. 



The eyes are disposed on the anterior part of the ccphalo- 

 thorax in two transverse rows ; the four intermediate ones 

 describe a trapezoid, the two anterior ones, which arc the 

 smallest of the eight, forming its shortest side ; the eyes of each 

 lateral pair are seated obliquely on a tubercle, and are con- 

 tiguous. The cephalothorax is oval, convex, glossy, with 

 slight furrows on the sides converging towards an indentation 

 in the medial line ; the lip is semicircular and prominent at the 

 apex; and the sternum is broad, heart-shaped, convex, and 

 glossy. These parts are of a very dark brown colour, tinged 

 with red, the lateral margins of the cephalothorax being the 

 darkest. The falccs are conical, inclined towards the sternum, 

 and armed with teeth on the inner surface; and the maxilla? 

 are enlarged where the palpi are inserted, and inclined towards 

 the lip. These organs have a red-bi-own hue. The legs and 

 palpi are provided with hairs, and are of a yellowish-red colour ; 

 the fourth pair of legs is the longest, then the first, and the 

 third pair is the shortest : each tarsus is terminated by three 

 claws; the two superior ones are curved and slender, and 

 the inferior one is inflected near its base. The abdomen is 

 oviform, glossy, convex above, and projects over the base of the 

 cephalothorax ; it is thinly clothed with short hoary hairs, and 

 has a black hue ; the sexual organs are minute and of a reddish- 

 brown colour, that of the branchial opercula being pale yellow. 



The sexes are similar in colour ; but the male, which is rather 

 the smaller, has the anterior part of the cephalothorax more 

 elevated, and has a narrow indentation directed backwards from 

 each lateral pair of eyes. Its palpi are short, and the radial and 

 digital joints have a dark-brown hue ; the humeral joint is 

 curved towards the cephalothorax, and the radial, which is 

 stronger than the cubital joint, has a small, curved, pointed 

 apophysis at its extremity, in front, towards the inner side ; 

 the digital joint is oval, convex and hairy externally, concave 

 within, comprising the palpal organs, which are highly de- 

 veloped, complicated in structure, with a black filiform spine at 

 their extremity, on the outer side ; this spine is curved in a 

 circular form, and within the curvature there is a prominent, 

 pointed, slightly curved spine, at the base of which there is 



