a first opening in {TAIL ~ surface portions} thereof adjacent said free extremity and in {HEAD ~ communication} with said passageway, 
a first opening in { TAIL ~ surface portions } thereof adjacent said free extremity and in { HEAD ~ communication } with said passageway ,
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH