Jackyso1993

The 40th P switch is called "Use items to blitz across the desert sands!", located the southwest of Mario Bros. Circuit (near the desert area)

The 39th P switch is called "Dash, dash, dash to the goal!", located the east side between the 20th & 38th P switch.

There might be the 38th P switch called "Weave around the treacherous tornadoes", located between 20th & 37th P switch.