THE CRIBELLATE SPIDERS 143 



quently the web is placed in plain view against a vertical surface. 

 The dry framework of the snare is commonly put down as a series 

 of lines from the central retreat, in which the spider stays most of 

 the time. Over the dry lines the cribellate silk is spun loosely, mak- 

 ing a thick mat upon which the spider runs. The spinning activities 

 are best observed at night; then the carding can easily be seen in 

 the rays of a flashlight. At this same time males may be found near 

 the female web. 



Amaurobius' egg sac is a flattened bag, attached to a stone and 

 usually covered over with a mesh of threads. The females stay with 

 the eggs for long periods, often being found with the sac some time 

 after the young have hatched. 



One of the commonest members of the genus in the eastern 

 United States is the domestic Amaurobius ferox, an immigrant from 

 Europe. This spider, which is much darker and somewhat larger 

 than the common bennetti, lives in cellars, under floors of houses, 

 and under wood and debris near human habitations. It is rarely 

 found far from man. 



Australia is particularly well supplied with spiders related to 

 Amaurobius; the habits of certain varieties are of special interest. 

 In the Jenolan Caves of New South Wales lives a gregarious species, 

 Amaurobius socialis, which spins great webs on the roof. These 

 giant reticles, one of which measured twenty feet in length and 

 more than four feet at its greatest width, hang from the roof and 

 are draped over the stalactites. They are closely and densely woven 

 to the consistency of a heavy fabric, such as a shawl, and are filled 

 with openings through which the spiders retreat to the interior. 

 Mating, egg-laying, and emergence of the young all occur within 

 the limits of the web, as among many truly gregarious spiders. 



Also in New South Wales may be found certain gregarious 

 spiders, perhaps relatives of Amaurobius^ which infest orange 

 groves. They mat the limbs with a thick covering of web so densely 

 woven that it affects the normal respiration and development of 

 the tree. The leaves wither and fall, the dead branches are left, 

 covered with unsightly webbing. Such spiders can become a pest 

 of nearly equal malevolence to tent-building insects. 



In the genus Dictyna are small spiders, averaging one eighth of 

 an inch in length, which are known by the unwieldly name of 

 "lesser mesh web spinners." Some few of these are brightly colored 

 in reds, browns, and tans, with here and there a brilliant yellow 

 spot, but for the most part their bodies are dull, clad plainly in gray 



