Also, {HEAD ~ the membrane} 62 completely covers {TAIL ~ the opening} 60 and thus prevents the opening from becoming clogged with grass 
Also , { HEAD ~ the membrane } 62 completely covers { TAIL ~ the opening } 60 and thus prevents the opening from becoming clogged with grass
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH