i6i AMERICAN SPIDERS 



almost everywhere in the world. A relatively large creature with a 

 pale white, elongate body a quarter of an inch long and legs two 

 inches long, it covers the ceilings and walls of our cellars and 

 neglected rooms with its maze of cobweb. 



In this section mention may be made of three families of prim- 

 itive line weavers that differ from the pholcids in having six as the 

 normal number of eyes. All are tiny creatures, rarely more than 

 an eighth of an inch in length, which live retiring lives in dark 

 places under stones and debris on the ground or in caves. The 

 relatively small number of species known from North America 

 reflects a failure to explore our caves adequately, rather than any 

 true sparsity of these minute animals. The sheet weavers of the 

 family Leptonetidae have relatively slender bodies and fine, long 

 legs. The eyes form a V-shaped figure, four close together in front, 

 the posterior median pair set quite far back. The web is an extensive 

 sheet of finely spun tissue placed in fissures on cave walls, and has 

 no definite maze of lines associated with it. Tiny white egg sacs 

 containing few eggs are placed on the walls near the web or hung 

 from the web itself by a thread. Several species are known from 

 the southern portions of the United States. Closely allied to the 

 leptonetids are some tiny cave spiders of Europe and Africa, the 

 Telemidae, which lack book lungs and have four orifices leading to 

 tracheal spiracles. Telema tenella of the eastern Pyrenees is eyeless. 

 In the western United States occur representatives of another fam- 

 ily of these primitive spiders, the Ochyroceratidae, which have 

 tiny globose abdomens much like those of the pholcids. The six 

 eyes are placed in a transverse row across the front of the head. 

 A typical species is Usofila gracilis, which, only one twenty-fifth 

 of an inch in length, occurs in Alabaster Cave, California; other 

 species live under debris on the soil outside caves. 



THE COMB-FOOTED SPIDERS 



The comb-footed spiders of the family Theridiidae are for the 

 most part thickset sedentary types that hang upside down from 

 the dry threads of irregular maze webs. Most are small spiders, 

 suspending their snares on plants with lines so fine that they are 

 often unnoticed, or hiding them in burrows or fissures in the soil 

 and under debris. Less well hidden are the webs of drab, house- 

 loving Theridion tepidariorum, which, soon covered with dust and 



