I'm 98% sure this is a stud hole (one of four in a line) on the upper surface of a B-25 wing located inboard of the engines on both the port and starboard wing. These stud holes were used to secure the main wing tanks into the aircraft. Does anyone have access to a B-25 to confirm that this is indeed one of the stud holes and provide some close up pictures of the inner wing sections. Most B-25 books do not provide a close up of the inner wings between the engines.http://img215.imageshack.us/img215/9808/b25wing.jpg
This image is from the B-25 manual showing a closeup of the stud hole.http://img835.imageshack.us/img835/1812/92390140.jpg
As always thanks for all your help and support
If this is above a cavity where a tank was installed I would say that is right as you say there is several in a row.
P-51 uses the same feature on the top and bottom of the wing to hold the tanks but the fittings are held in place by 4 screws rather than the rivets.