The longitudinal opening 20 will also allow the animal {HEAD ~ access} to {TAIL ~ the ball} 18 while it is in the track 
to
The longitudinal opening 20 will also allow the animal { HEAD ~ access } to { TAIL ~ the ball } 18 while it is in the track
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH