There is an L-shaped molded rubber hose that goes on the the outboard fitting.  It's a vent for the carb bowl and points straight down.  
Shown in one of the photos is the crankcase vent line.  There is a short hose connecting it to the back side of the air cleaner box.
This carburetor has been discontinued.  Every other carburetor under the sun has a $9 ebay made-in-china replacement but not this one.