Interesting.
Perhaps the mast has a large diameter and the four spider legs protrude out of the mast, below the rotor plane, through four holes. Just a guess.
The following is quoted from J. Gordon Leishman, and might be of some interest:-
"Raul Hafner introduced the "spider" cyclic-pitch control system to autogiros. This provided a means of increasing collective pitch and also tilting the rotor disk without tilting the rotor shaft with a control stick as in de la Cierva's direct control system. Hafner used this design in his third autogiro, the AR-3, which flew in 1935."
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[This message has been edited by Dave Jackson (edited 15 March 2001).]