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Psyche 
[September-December 
soni at the time and ones that are not. Various gnaphosid species 
are among the most frequent nest associates. Occasionally dead 
P. johnsoni are found inside their nests. On two occasions, both 
in the Wind River Range of the Rocky Mountains, a gnaphosid, 
Drassodes neglectus (Keys), was found inside a nest with a dead 
P. johnsoni female. In each case, the salticid was dry, had rup- 
tures in the cuticle that resembled fang wounds, and had the ap- 
pearance of having been consumed by another spider. In one 
case, the nest contained a P. johnsoni egg case. The silk around 
the eggs had been pulled away, but the eggs had not been eaten. 
P. johnsoni tend to be 10 to 12 mm in length, and the gnaphosids 
were of comparable size. These observations suggested that 
large gnaphosids prey upon P. johnsoni in their nests and per- 
haps consume the eggs as well. Further observations were car- 
ried out in the laboratory, using another gnaphosid species, 
Herpyllus hesperolus (Chamberlin). This species was a common 
nest associate of P. johnsoni in the Coastal Range of California, 
which was more accessible from my laboratory in Berkeley. 
Methods 
Three sets of observations were carried out: H. hesperolus 
encountering P. johnsoni inside their nests, P. johnsoni males 
encountering H. hesperolus occupying the nests of P. johnsoni 
females, and P. johnsoni males encountering empty nests of 
both P. johnsoni females and H. hesperolus. The latter were 
included in order to determine whether P. johnsoni males can 
discriminate between the two types of nests. 
Both the salticids and the gnaphosids were collected from 
habitats near the San Francisco Bay in California. They were 
maintained individually in 10 cm long plastic cages, built accord- 
ing to the design described by Jackson (1974), that provided a 
continual supply of house flies ( Musca domestica ) and moisture. 
Both mature and immature gnaphosids were used. Although 
P. johnsoni almost always constructed nests during the first day 
of occupancy of their cage, the gnaphosids built much less fre- 
quently, primarily just before molting. Each spider was used 
in only one observation, except for the paired observations on 
each male in the nest discrimination experiment; and each time 
the spider (and nest) used was chosen randomly, using a random 
