THE HUNTING SPIDERS 219 



bv any other spiders; a display of this ornamentation is part of 

 their courtship ritual (see Chapter V). Quite friendly little crea- 

 tures, they sometimes sit upon a finger and follow one's every move 

 with an attention not ordinarily manifest in arthropods bound by 

 complex instinctive patterns. Fine eyesight has made them the out- 

 standing spider extroverts. The largest eyes of our spotted Phidip- 

 pus audax are capable of receiving a sharp image (perhaps ensuring 

 recognition of another's species and sex) at a distance of ten or 

 twelve inches. Awareness of moving objects by the four pairs of 

 eyes, each of wriich receives different-sized images, is possible at a 

 much greater distance. The jumping spider spies its prey in the 

 distance, creeps slowly forward until very near, then leaps sud- 

 denly upon it. 



Almost all the jumping spiders are small; few much exceed half 

 an inch, and most fall far short of that length. The short, stout 

 body, the rather short legs, and the distinctive eye arrangement 

 make them one of the most easily recognizable of all groups. The 

 rectangular cephalothorax is large and wide, squared-off in front, 

 and often quite high. As in the *wolf spiders, the eyes are set in 

 three distinct rows: four, two, and two. Those of the front row 

 (small in wolf spiders) are greatly enlarged the middle pair espe- 

 cially, which resembles large, smoky pools, and, well supplied with 

 rods, give the most perfect image. Above the front row is a second 

 row of two tiny eyes, and behind these a third row of two larger 

 ones. The abdomen is often oval, but may be thick and wide, or 

 greatly elongated, to conform with the cephalothorax. Over the 

 whole body is usually present a thick covering of colored hairs 

 forming an even blanket, as well as longer hairs and spines that add 

 special adornment according to the species. 



These hunters run, leap, and dance gracefully on legs of moder- 

 ate length. The first pairs are usually longer and thicker than the 

 hind ones, especially in the males, whose front legs are in addition 

 bedecked with conspicuous plumes and ornaments prominently 

 displayed during courtship. It is a surprise to find the hind legs, 

 which are most used in jumping, neither modified nor strengthened 

 as they are in such animals as kangaroos and frogs. Apparently the 

 small size and slight weight of the spiders make possible those tre- 

 mendous leaps up to forty or more times the body length. The leg 

 tarsi are provided with brushes of hairs, and their tips have well- 

 developed adhesive claw tufts. They leap from stem to stem with 

 ease and seeming abandon, and are saved from falls by dragline 

 threads laid down wherever they go. They have been observed to 



