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COLLEGE ZOOLOGY 



ground tunnels lined with silk and fitted 

 with trap doors. Ex. Pachylomerides au- 

 douini of our south, and Bothriocyrtum 

 californicum of the west coast. 



3. Dictynidae. Hackled-band weavers. These 

 spiders possess an accessory spinning organ, 

 the cribellum (Fig. 163). The special silk 

 emitted from this organ is combed out 

 by the calamistrum of the fourth meta- 

 tarsus. The irregular webs are constructed 

 among plants or under debris. Ex. Dictyna 

 muraria of wide distribution. 



4. Pholcidae. Long-legged spiders. Most of 

 these are pale, small-bodied, weak-jawed, 

 long-legged spiders, which shun the light. 

 Their irregular webs are built in base- 

 ments and similar situations. Ex. Pholcus 

 phalangioides of wide distribution. 



5. Theridiidae. Comb-footed spiders. A very 

 large family of spiders, most of whose 

 members are small in size. The fourth 

 tarsus is provided with a row of serrated 

 bristles forming a comb, used for flinging 

 a very viscid silk which swathes the prey 

 captured in their irregular webs. Ex. Theri- 

 dion tepidariorum (Fig. 164), the cosmo- 

 politan and common house spider which 

 builds cobwebs in the corners of rooms. 

 Latrodectus mactans (Fig. 168), the black 

 widow, which is found in most of North 

 and South America, but commonest in 

 the warmer regions. 



6. Linyphiidae. Sheet-web weavers. Small 

 spiders which build webs usually provided 

 with a more or less horizontal or curved 

 sheet from the under surface of which they 

 suspend themselves upside down. Many 

 build among plants, but large numbers are 

 found among the dead leaves and other 

 litter close to the forest ground. They are 

 more abundant in temperate and arctic 

 regions than in subtropical and warmer 

 zones. Ex. Linyphia marginata, the filmy 

 dome spider. 



7. Araneidae. Orb weavers. A very large family 

 of spiders, the members of which, if they 

 build a web at all, construct a cartwheel- 

 like structure known to all who have 

 walked through the woods in late summer. 

 While the foundation and radii lines are 

 not sticky, the spiral thread is quite viscid 

 and serves to snare the prey. The spiders 



have strong jaws and are usually beautifully 

 marked. Ex. Argiope aurantia (Fig. 161), 

 the black and orange garden spider, which 

 builds its web in grass and among bushes 

 exposed to sunlight, and in the hub of 

 which it stands head down. 



8. Agelenidae. Funnel-web weavers. These 

 spiders build a more or less horizontal 

 sheet web, over which they run in an up- 

 right position, and at one side of which 

 they hide in a cone-shaped retreat. The 

 threads are not sticky, and the spider does 

 not swathe the prey, but depends upon 

 lightning speed to run out and seize in its 

 jaws any insect that happens to touch the 

 threads. Ex. Agelenopsis naevia, which 

 builds its web most commonly in grass, 

 but also among shrubbery and stone 

 fences. 



9. Pisauridae. Nursery-web weavers. Most of 

 these are large spiders which build no 

 snares, but hunt their prey along water 

 courses, in grassy areas, and forests. The 

 large spherical egg sac is carried about by 

 the mother under her sternum. Shortly be- 

 fore the emergence of the progeny, most 

 species fasten the sac among some leaves 

 and construct a nursery web around it, 

 standing guard until the spiderlings 

 emerge. Ex. Pisaurina mira. 



10. Lycosidae. Wolf spiders. These are me- 

 dium to very large spiders, with keen eye- 

 sight, strong legs, and powerful jaws. 

 They run about actively, both day and 

 night, hunting their prey. Some hide in 

 natural cavities in the ground, others con- 

 struct vertical burrows somewhat like those 

 of the trap-door spiders. The males of 

 many species go through elaborate court- 

 ship dances before the females. Ex. Lycosa 

 carolinensis, our largest species. 



11. Gnaphosidae. Ground spiders. The ma- 

 jority of these are medium-sized and run 

 very rapidly over the ground, usually hid- 

 ing under stones and logs. They build no 

 snares, but may construct retreats in 

 which they hide and in which the egg 

 sac is fastened. 



12. Thomisidae. Crab spiders. These spiders 

 walk sidewise as readily as forward or back- 

 ward, and many have short stocky bodies. 

 While most are dark-colored and live on 



