An arcuate shaped lower jaw is provided with {HEAD ~ an inner end} and {TAIL ~ a backside} 
An arcuate shaped lower jaw is provided with { HEAD ~ an inner end } and { TAIL ~ a backside }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL