THE AERIAL WEB SPINNERS 161 



the daddy longlegs. The leg tarsi are often made flexible by the 

 presence of numerous transverse creases or sutures in the integu- 

 ment. Eight eyes, set close together on an elevated tubercle, are 

 usually present, but the anterior median pair may be lost, and in 

 some cave species all eyes may be reduced in size or completely 

 missing. The long-legged pholcids occupy a position between the 

 higher sedentary types and the spiders of very primitive level. 

 Their derivation from prototypes similar to the present cribellate 

 Filistatidae through loss of the cribellum and modification of a few 

 other features is quite plausible. Although commonest in warmer 

 regions, they are quite numerous in temperate areas, as is well 

 shown by the presence of eight genera and about forty species in 

 the North American fauna. 



The pholcids spin, in dark places, loose, irregular webs, some- 

 times with a distinct closely woven sheet. Males live in the same 

 webs as the females and resemble them closely, but may be recog- 

 nized by the great size of the palpi, which are enlarged to form 

 thickened appendages. The females carry the eggs in their chelic- 

 erae, glued together into a spherical ball and tied lightly with a few 

 silken lines; later they may be found holding the mass of recently 

 hatched young. Most pholcids are pale white or yellow, but some 

 are more gaily colored in pastel greens and blues. Many become 

 domestic, especially in our southwestern states, where species of 

 several genera find conditions in houses and buildings quite as suit- 

 able as in the open. 



These long-legged line weavers are like some of the orb weavers 

 in having a most interesting habit that becomes operative when 

 prospective insect prey is caught in the net. They shake the web 

 violently to hasten thorough entanglement, then, when the capture 

 is being made, twist the victim around and swathe it with silk. This 

 aggressive action turns into a defensive gesture when the spider is 

 disturbed, and it pumps up and down on its long legs so violently 

 that it becomes a mere blur. This whirling or shuttling, which be- 

 comes increasingly violent when the stimulus is repeated three or 

 four times, usually takes place when the web or the body of the 

 spider is touched, but on occasion other stimuli provoke the re- 

 sponse. When thoroughly aroused, the spider retreats to dark re- 

 cesses within the web, or drops down from it to run rapidly and 

 hide away in some dark corner. 



The best-known member of the family is the long-legged cellar 

 spider, Pholcus phalangioides (Plate XIX), which occurs in houses 



