THE HUNTING SPIDERS 233 



where they feed upon tiny animals ignored by larger spiders. Many 

 are colored bright orange and have hard plates on the abdomen; 

 others are white or pale-yellow, with soft abdomens. These pretty 

 spiders, of which fewer than twenty species are known to occur in 

 our southern states, run rapidly; some are fine jumpers when dis- 

 turbed. One of the smallest is Orchestina saltitans, a midget about 

 one twentieth of an inch long with a soft abdomen. It penetrates 

 quite far into the Northeast, where it lives for the most part indoors 

 as a domestic spider. It may occasionally be seen hanging by its 

 threads from a lampshade, foraging in the medicine closet, or run- 

 ning among books on desks. 



The most interesting members of this whole series are the six- 

 eyed tube weavers of the family Segestriidae. These cylindrical 

 spiders, which retain the unpaired claws on all the tarsi, have the 

 first three pairs of legs directed forward, and the front pairs, with 

 which they hold victims, armed below with numerous stout spines. 

 A typical member is Ariadna bicolor, half an inch long, which is 

 found almost everywhere in the United States; it has a purplish 

 brown abdomen, and light brown cephalothorax and legs. Two 

 related genera, Citharoceps and Segestria (the latter having several 

 well-known species in Europe), occur only in California. 



The retreat of Ariadna is a long, slender tube placed in a suit- 

 able crevice, with the silk continued outside and around the mouth 

 opening as a silken collar. From the inner edge of the mouth orig- 

 inates a series of heavy lines that radiate outward like the spokes of 

 a wheel, and that are attached at their ends a short distance beyond 

 the collar. These radii, often two dozen or more, do not lie flat 

 against the substratum, but are supported above the surface by little 

 silken piers, one near the opening at the edge of the collar and the 

 other out beyond the collar. The spider sits just within the tube, 

 its six legs directed forward, in position to leap. The touching of 

 one of the trap lines brings it out with surprising swiftness, like a 

 jack-in-the-box, to the spot where the unlucky insect has tripped. 

 It seizes the victim, then, carrying it, instantly backs into the tube 

 again. Even such formidable prey as a wasp is held almost helpless 

 within the narrow tube so narrow that the spider itself is unable 

 to turn. 



The remaining group of primitive hunters includes Scytodes, as 

 well as the quite diverse types conventionally placed in the family 

 Scytodidae but representing several distinct lines of family rank. 

 In all these spiders the chelicerae are soldered together at the base 



