2 fuel lines from gas tank under the hood?

On my 1972 dart, there are 2 metal fuel lines on the passenger side that end right before the front wheel under the hood. one of them is the fuel feed that is hooked to my fuel pump. The other is just sitting there open to the atmosphere and i dont like it just sitting there open. Wondering first, what this other metal line is for and what can i do with it so nothing can get into it and plug it up..? If its a vent line, is it safe to be just open under the hood like this?