combine xargs with EOF

[giuseppe . amatulli]

Hi
i'm using often xargs to run process in parallel

ls *.txt | xargs -n 1 -P 10 bash myscript.sh 

where myscript.sh is (for examples of course is longer):
echo $1

i would like to perform the same operation using the EOF syntax and import the 
arguments inside the eof

I tried 

ls *.txt | xargs -n 1 -P 10 <<
echo $1
EOF

also with the option -E and -e but did not work 

any ideas?
thanks Giuseppe