141 



separated gonerically from Nericne ; that is to say not as that 

 genus is at present characterized and limited ; but they may be, 

 for the most part, easily distinguished (at least in tho 

 male sex) by the structure of tho fore part of the caput ; this 

 portion is, excepting in a few instances, moro or less elevated 

 protuberant or prominent, and the eyes are grouped moro or less 

 closely upon or round the elevation. In Nericne, on the contrary* 

 the eyes are always external to any eminence on the caput ; and, 

 oxcepting in a comparatively fow instancos, there is no eminence 

 at all upon it. The fomales of Walclienacra, excepting those of 

 a fow specios, aro dostituto of the form of the caput so charac- 

 teristic of the males, and are, mostly, quite indistinguishable 

 from tho fomales of Nericne. In colours the spiders of the two 

 genera aro usually similar ; different dopths, however, of colour- 

 ing are good specific characters in Walchenacra as they are also 

 in Nericne ; the various species of Walchenacra aro also found in 

 similar situations, and (so far as t\xej are known) their habits 

 and snare are similar. Tho armature of the logs consists o 

 hairs, and very slender bristles only ; theso latter are generally 

 erect or very prominent, and never attain a spinous nature as do 

 those of some species of Nericne. 



The genus WalcTcenacra contains some of the smallest known 

 spiders— one, W. diceros, Cambr. — measuring less than half a 

 line in length. 



The differences in the form and structure of the caput con- 

 stitute the most tangible, as well as tho best, specific characters 

 of the male. Fifty-seven spocies are at present known as 

 British, and of these thirty-eight have been found in Dorset- 

 shire. 



A Prussian arachnologist, Herr Menge, has constituted 

 numerous genera out of the various species of Nericne and 

 Walchenacra, but as most of his genera are chiefly based on almost 

 microscopic characcers, derived from a portion of tho male struc- 

 ture only, they will hardly (at any rate not all of them) retain 

 their place in a scientific system. 



