Hi JD
Looks like a centrifugal 'trash' pump to me, it's been lots of years since I had anything to do with them, and it wasn't much then.
The trash bit is because they would handle gravel etc. when clearing out flooded trenches and the like, as I recall the little compressor is actually a vacuum pump, the idea being that the centrifugal pump couldn't draw enough vacuum to lift the water into the pump housing if it more that a foot or so above the water level. The vacuum pump would draw the liquid into the centrifugal pump from the discharge side, and as the pressure on the outlet side rose a flap valve or similar would shut off the air passage and the water would leave via the 'lay flat. (like fire hoses) hose. The suction hose would have been rigid, to allow for the negative pressure of the suction side and have a strainer..
From memory the hose connections are called Bauer fittings.
Mind you I could be well wrong about all of the above!
It looks like it may have been submerged, not unlikely bearing in mind what they did for a living, does it turn over?
Any makers marks on the pump casting?
Best of luck with it.
Cheers
Stef