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Psyche 
[Vol. 87 
further observations on other aspects of its natural history and 
behavior, including web forms and their construction, the structure 
and function of the sticky ball, variations in prey species, egg sac 
construction behavior, and rates of egg sac production. These 
observations seem to link Mastophora to both araneids such as 
Cyrtarachne, Poecilopachys, and Pasilobus which spin more nearly 
typical orb webs, and to the completely webless Celaenia and 
Taczanowskia. 
Methods and Study Sites 
The main study site and the observation methods are described in 
Eberhard, 1977. The spiders were sedentary, seldom moving more 
than 10-20 cm in a night and usually returning day after day to the 
same daytime resting site where a pad of silk gradually accumulated. 
These sites were extremely exposed; one was on the barb of a barbed 
wire, and others were on fence posts, the upper surfaces of leaves, etc. 
in an open field. During the day in Cali the spiders sometimes 
experienced temperatures of up to at least 42° C combined with brisk 
(>10 kmph) winds. 
Additional observations were made in open areas near the edge of 
Lago Calima (el. 1400 m) in grassland with scattered small bushes 
and trees, where spiders were relatively common in September, 1977, 
but absent in January, 1979.. 
Unless otherwise noted, all descriptions of behavior refer to 
observations of mature females. 
Mastophora dizzydeani new species 
Figure 1-9 
Dr. Willis Gertsch kindly studied male and female specimens, and 
stated (in litt.) that “I am confident that it represents an undescribed 
species. Like Dr. Gertsch, I have been unable to match this species to 
any published description, and keeping in mind the overworked state 
of most spider taxonomists plus the parasitic relationship which 
behaviorists and ecologists generally enjoy with them, will undertake 
the description of this new species. 
Etymology. Since this spider’s livelihood depends on throwing a ball 
fast and accurately, it seems appropriate to name it in honor of one of 
the greatest baseball pitchers of all time, Jerome “Dizzy” Dean. 
All measurements in mm; colors in parenthesis from living spiders. 
