fuel tank lines?

On my 1972 dart swinger, there are 2 metal lines that come from the gas tank and stop under the hood. On one of them, i have a rubber hose running to the fuel pump and the other one is just open. I ve been running it like this forever but dont like the fact its just open. What is it supposed to go to? Im assuming it originally went to a charcoal canister or something? if so, i dont have that canister now, what should i do with it? Im sure it has to be open to vent the tank but is there something that can keep stuff from getting in it?