Which sentence is better?

1. On May 15, 1941-July 17, 1941, DiMaggio held the longest consecutive game hitting streak (56 games).

2. On May 15-July 17, 1941, DiMaggio held the longest consecutive game hitting streak (56 games).

Please Help!!
Thanks!!

Neither. How can a time period be refered to as "on" ?

During?
Between..?