{TAIL ~ The rear wall} of the second case is in {HEAD ~ communication} with the rear wall of the first case 
{ TAIL ~ The rear wall } of the second case is in { HEAD ~ communication } with the rear wall of the first case
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH