a hydraulic motor operatively connected to {HEAD ~ each} of {TAIL ~ said first and second screw conveyor members}; and 
of
a hydraulic motor operatively connected to { HEAD ~ each } of { TAIL ~ said first and second screw conveyor members } ; and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH