Guitar by Schultz, Fiddle by Vandiver and Bluegrass by Monroe

Arnold Schultz was a country and blues man who's blues licks added to Monroe's flavorful arsenal of playing style.
Pictured above with Monroe's fiddling Uncle Pendleton 'Pen' Vandiver (mom's brother), they were credited by Monroe as being the primary influences to his inimitable musical style that he would come to coin as Bluegrass.

Nice.

info as referenced from the Kentucky Blues Society at:
http://www.skybluessociety.org/history.htm
and wikipedia @ http://en.wikipedia.org/wiki/Bill_Monroe