Looks like a streamlined version of the Northrup Raider STOL transport, manufactured for the USAF shortly after WW2.
Eventually air regulations only required a stewardess if there were more than 20 passengers on board. That is why a lot of DHC-6 Twin Otters, Beechcraft 99s and other feeder liners only had 19 seats. In comparison, stripped Twin Otters routinely carry 25 skydivers.