232 



WEB-SPIDERS. 



a side-walking spider (Xysticus viaticus). Female, left-hand figure : male, 

 right-hand figure (enlarged). 



to oscillate rapidly until it and its occupant almost disappear from view. The 

 commonest British members of the family belong to the genus Araneus, of which 

 the cross or garden spider (A. diadema) is so abundant in gardens late in summer 

 and autumn. Some of the tropical forms, such as Nephila, are of enormous size, 

 and construct huge webs strong enough, it is said, to arrest the flight of small birds. 

 The males are veritable pigmies, as compared with the females. Also belonging to 

 the family are those curious tropical spiders of the genus Gastracantha, which are 

 protected from enemies by having the integument of the abdomen hard, horny, 

 and armed with spines. The figure on p. 231 of a species of Tetragnatha re- 

 presents another toler- 

 ably common member 

 of this family. It is 

 characterised by its lon£ 

 and slender abdomen, 

 and enormousty strong 

 projecting mandibles. 



We now come to 

 spiders differing from 

 nearly all the preced- 

 ing in that they obtain 

 their prey by hunting 

 instead of constructing 

 snares. The first tribe 

 of these, the Laterigradce, derives its name from the fact that its members walk with 

 a side, crab-like gait, a power which they owe to the rotation of their legs back- 

 wards in such a manner that the lower surface is turned forwards and the front 

 upwards. The two first pairs of legs are longer and stronger than the others ; the 

 tarsi have but two claws, and the eyes are arranged in a double row. Of the 

 families the so-called crab-spiders (Thomisidce) include small squat-looking forms, 

 with the two hinder pairs of legs weaker than the two front pairs. The carapace 

 is broad and often biangulate in front, and the abdomen frequently wider behind 

 than in front. These spiders are mostly sluggish and noticeable for their protective 

 coloration. Those frequenting flowers for the purpose of seizing the insects 

 that visit them possess the power of changing their tints to suit that of the blossom 

 in which they take up their abode. The egg-cocoon is sometimes rolled in a leaf, 

 sometimes left uncovered ; but after constructing it the female forsakes her 

 wandering life to watch over her offspring. The Heteropodidce differ in having 

 the mandibles more strongly toothed. The family is represented in Europe by a 

 few spiders of medium size (Sparassus, etc.), but in the tropics by many of large 

 size. One of the best known is the tropical house spider (Heteropoda venatoria), 

 a large, long-legged species, introduced almost all over the hotter parts of the 

 world. The female carries her lenticular cocoon tucked to the lower surface of 

 the cephalothorax. The annexed figure of a South African spider (Palystes) 

 shows the characteristic size and structure of the members of this family. 



Passing over certain unimportant groups, we reach the running spiders, 

 Citigradce, which live on the ground, and capture prey by speed of foot. 



