Psyche 
[September 
162 
did they become disoriented. It is likely that: (1) their ability to 
achieve numerous, partial hematodochal expansions during insertion 
attempts provided sufficient feedback for maintenance of the copula- 
tory mode, and (2) the availability of the palps for sensory purposes 
provided input for orientation purposes. 
The early occurrence of courtship after mount by some of the 
males lacking one palp suggested that there was a relatively inde- 
pendent insertion tendency for each palp. Even though able to suc- 
cessively insert the remaining palp, such males were still motivated 
to insert the absent palp and, when unable to do so, switched back to 
pre-copulatory display behavior for a period of time rather than 
continue to use the functional palp. 
A relative independence of insertion tendency for each palp was 
also suggested by the change in behavior towards the end of copula- 
tion in males paired with females having one copulatory pore sealed. 
Such males continued their insertion attempts on the unavailable 
side but decreased their visits to the functional side. This indicated 
that the motivation underlying insertions of the functional palp 
had decreased to a minimal level as a result of numerous successful 
insertions. 
Peripheral input from the palps seemed important for the male’s 
positioning on the female. Two- thirds of the males in which both 
palps were unavailable showed disorientation at various times while 
above the female. Since disorientation usually involved a 180° mis- 
alignment, it seemed likely that input from other parts of the body, 
probably the sternum and legs, served for maintenance of a medial 
position (above and in line with the female) and that input from 
the palps determined the correct anterior-posterior orientation. This 
is quite different from the control system in a linyphiid spider studied 
in this regard (Rovner, 1967). Palpless male Linyphia triangularis 
maintain a normal position throughout “copulation” (both partners 
hanging inverted, facing in opposite directions, and the male’s head 
pivoting on or near the female’s chelicerae). In the latter case, in- 
formation from tactile hairs on the anterior dorsal point of the male’s 
pars cephalica (and probably the legs also) suffices for orientation. 
Most of the males copulating with females whose genital openings 
were sealed performed pseudo-insertions. This behavior was a re- 
sponse to sub-normal releasing stimuli, in that the entire cycle of 
events associated with a palpal insertion occurred without successful 
engagement of the embolus. It seemed that the threshold for release 
of complete hematodochal expansion gradually lowered during a 
succession of insertion attempts. At some point, an initiated expan- 
sion went to completion without the normally necessary engagement 
