The two groovelike indentations 17 on both sides of {HEAD ~ the insertion slit} 9 are in {TAIL ~ alignment} with one another and with the insertion slit 
The two groovelike indentations 17 on both sides of { HEAD ~ the insertion slit } 9 are in { TAIL ~ alignment } with one another and with the insertion slit
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH