What kind of planes are on this old photo?
This is a formation of Curtiss-Wright AT-9s officially known as the Fledgling, but also known as the Jeep. 

A high resolution version of the photo is available here: A formation of AT-9s over the Gulf of Mexico. USAF Photo 

The National Museum of the US Air Force has restored an example painted to represent the aircraft in the foreground; more information can be found here: AT-9