The floatplane is certainly an oddity and obviously not quite what is stated on the caption.
It seems to be of the Kingfisher ilk but has some features strongly reminiscent of the Curtiss SO3 Seamew family. Note the in-line engine (yet apparently with Wasp type radial cooling gills) and the single cantilever strutted tip floats. Also that fin and rudder assembly is enormous.
The photo has been touched up somewhat which doesn’t help.

That’s the machine that came to mind when I saw the picture and Iwas planning to throw in the Curtiss name but you beat me to it. I couldn’t remember the designation and, as I’m at work, I have no access to my reference books.