Superfamily Argiopoidea 



line, crossed by a crescent-shaped mark on the highest part. 

 The abdomen is grayish, with brown spots of various shapes 

 (Fig. 566). The abdomen is as high as long, and bears a pair 

 of humps on the highest part. 



The egg-sac of this species (Fig. 567) is very characteristic 

 in form. It is nearly spherical and is suspended by a cord of 

 coarse threads, which are continued over the egg-sac as a loose 

 network. I have found it most often attached to cliffs in shady 

 places. 



Family THOMISID^ (Tho-mis'i-dae) 



The Crab-spiders 



The crab-spiders are so called on account of the short and 

 broad form of the body, the crab-like attitude of the legs in most 

 of the species, and the curious fact that these can walk more 

 readily sidewise or backward than forward. In one of our genera 

 (Tibellus), however, the body is long and slender. 



The first and second pairs of legs in the more typical forms 



are much stouter and longer 



than the third and fourth pairs; 

 and in these forms the third pair 

 of legs is directed forward like 

 the first and second pairs (Fig. 

 568). The tarsi are furnished 

 with two claws. The eyes are 

 small, dark in colour, and ar- 

 ranged in two rows, which are 

 almost always recurved. The 



lower margin of the furrow of Fig. 568. a crar-spider 



the cheliceras is indistinct and 



unarmed; the upper margin is either unarmed or furnished with 

 one or two teeth. 



These spiders spin no webs; some species run swiftiy and 

 pursue their prey, while others of slower gait depend on their 

 concealing colours and lie in wait for it. They live chiefly on 

 plants and fences, and in the winter hide in cracks and under 

 stones and bark. Most of the species are marked with gray and 

 brown, like the bark upon which they live. Some species con- 

 ceal themselves in flowers, where they lie in ambush. These 

 are brightly coloured, like the flowers they inhabit, so that insects 



521 



