valve means for selectively permitting and terminating {TAIL ~ a flow} of said contents from said {HEAD ~ reservoir} 
valve means for selectively permitting and terminating { TAIL ~ a flow } of said contents from said { HEAD ~ reservoir }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD