146 AMERICAN SPIDERS 



general appearance and in superficial features. However, Zoro- 

 crates y the only American representative, still relies on an expan- 

 sive web to snare its prey. The net, resembling to some extent that 

 of Amaurobius y is usually placed beneath stones, and made into an 

 effective trap by spinning many viscid hackled bands over its dry 

 framework. It may be that Zorocrates' scopular brushes contribute 

 to better movement over the surface of its web, or perhaps that this 

 spider is on its way to becoming a vagrant form and therefore 

 spends part of its time outside the limits of its snare. Several species 

 of Zorocrates live in our southwestern states, but they are still little- 

 known creatures. 



In the related group of cribellate spiders, Acanthoctenus, known 

 only from tropical America, true tarsal claw tufts are present in 

 addition to the thick scopular brushes beneath the metatarsi and 

 tibiae. These flattened creatures often sit under bark, closely ap- 

 pressed to the surface, and move with great speed when they are 

 touched, their claw tufts aiding them in holding on to surfaces, as 

 with the ecribellate vagrants. Acanthoctenus combines a sedentary 

 aptitude with running ability. It spins a loose web, embellished 

 with sticky bands to entangle its prey. 



One of the few cribellates that has attained a nearly cosmopoli- 

 tan distribution is Oecobius annulipes, a tiny spider less than one 

 eighth of an inch in length, which is one of the few American repre- 

 sentatives of the curious family Oecobiidae. The generic name of 

 this spider signifies "living at home," and well characterizes these 

 dwarfs found in and on the walls of dwelling places. The micro- 

 scopic webs of Oecobius are frequently spun over cracks in the 

 sides of buildings; they are only about the size of a postage stamp, 

 but seem quite adequate to entangle the tiny insects used for food. 

 The spider, which is pale white or pale brown and marked with 

 distinct black points, is common in the southern part of the United 

 States and has long gone under the name parietalis, but it is now 

 known to be identical with the universally distributed annulipes. 

 Several related species of Oecobius ocur in the southern part of this 

 country, living under stones, on trees, or on buildings. 



THE AERIAL HACKLED BAND WEAVERS 



The most pronouncedly aerial of all the cribellate spiders are 

 those of the families Deinopidae and Uloboridae, groups largely 



