﻿366 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



leaves and refuse matter from their food, and are over-lined with 

 their thick, sticky threads, thus affording an advantageous back- 

 ground for the spiders, for being of the same color as the nests they 

 are thus given necessary protection. Numbers of sheet-like webs 

 radiate from the nest, in one or many directions. At a given spot 

 five or six nests are often found built over the leaves of the prickly 

 pear, with a number of connecting webs — thus establishing means 

 of inter-communication. These hanging webs are peculiarly con- 

 structed. A number of strong and non-sticky threads are irregularly 

 laid to form the warp while the woof of sticky threads closely laid 

 in a zig-zag manner, connect the non-sticky threads issuing in all 

 directions, sometimes establishing communication between one nest 

 and another, like bridges to cross the intervening space. 



The number of spiders in a nest varies from 40 to 100. Males and 

 females occupy the same nest in the proportion of 7 to 1, though 

 sometimes the females are less numerous. 



The creature itself is not less interesting than its nest. It is more 

 or less a compact animal about the size of our ordinary vagrant 

 spider of the family Attidse. 



The female 



Millimeters. 



Total length cephalic thorax and abdomen 8 



Abdomen 4 



Cephalothorax 4 



The male 



Total length 6 



Abdomen 3 



Cephalothorax 3 



This spider belongs to the family Eresidse. It is ash-colored, 

 this tint being due to the color of the hairs over its body surface. 

 Three longitudinal white stripes mark the dorsal surface of the 

 abdomen. The limbs are striped gray and brown. A number of 

 dark lines makes the abdomen appear segmented, but closer exam- 

 ination shows them to be only external figurations. There are ap- 

 proximately six pairs of dots arranged on either side of the leaf-like 

 patch on its dorsal surface. 



The ventral surface of the abdomen bears two black irregular 

 spaces, the lower one of which contains the spinnerets, which are six 

 in number, with a cribellum. The cephalothorax is ash-colored with 

 an anterior prominence that forms the head. The cephalic groove 

 which is well marked in most spiders is absent here. The eight eyes 

 are arranged in three rows as in Lycosidpe. The first two rows, of 



