68 
Psyche 
[March 
spiders within 1 mm of the string were counted. The web was 
arbitrarily divided into 3 sections. Two transects were placed onto 
each section on each census-day; and there were 1 1 census days, 
each 2 to 3 days apart. A “census” was defined as the sum of the 
spiders found on the two transects on a given section on a given 
census-day. 
Census Areas 
Mallos niveus 
Three aggregations of M. niveus were censused in Guanajaato 
(Guanajaato, Mexico), each under a different window sill on 
exterior walls of buildings in the city. The webs were arranged in 
horizontal straight lines, and the length of the aggregation was 
defined as the distance between the first web at one end and the last 
web at the other end (Census Area No. 1, 54 cm; No. 2, 87 cm; No. 
3, 273 cm). The distance to the nearest conspecific not in the 
aggregation was greater than length of the aggregation in each case. 
Mallos trivittatus 
Census Areas Nos. 1, 2, and 3 were at East Turkey Creek in the 
Chiracahua Mountains (Arizona, USA). The creek passes through a 
1.8 m diameter metal culvert, with an interior surface area of 88m 2 . 
Almost the entire interior of the culvert was covered by a single 
enormous web complex. The bottom of the culvert was covered by 
water; and in the immediate vicinity of the water, web units were 
scarce. Subtracting these parts of the culvert, the web complex was 
conservatively estimated to be 79 m 2 in area. Census Areas Nos. 1 
and 2 were each inside the culvert, within 2 m of opposite entrances 
and 1.5 m above the bottom of the culvert. Census Area No. 1 was 
56 cm X 50 cm; No. 2, 60 cm X 56 cm. Census Area No. 3 was a web 
complex (54 cm X 42 cm) 30 m from the culvert, on a large boulder 
(ca. 2 m high) beside the creek. The boulder was overhanging the 
ground, forming a shallow cave (ca. 1 m from ground to top; 0.5 m 
from entrance to back). The web complex was on the upper surface 
of the cave. 
Census Area No. 4 (56 cm X 32 cm) and No. 5 (56 cm X 56 cm) 
were web complexes on rock ledges near Estes Park (Colorado, 
USA). Each was 1 to 2 m above the ground. Census Area No. 6 was 
a web complex (124 cm X 34 cm) on the upper surface of a shallow 
