What is the name of the hose that goes from the valve cover to the air cleaner on my Chevy 350 tbi?

I have a 1990 Chevy Caprice with a factory Chevy 350 tbi engine (vin code "7"). On the rear of the passenger side valve cover there is a hose that, from pictures i have seen, is supposed to connect to the side of the air cleaner, but its is missing the connecting hose. What is it called? Do I really need it? What is it? This is my first project car and if anyone could help me out it would be greatly appreciated. Thank you.