[Dave at Pelican Parts]

I don't know the official name. We usually call it the head vent tube. It is pressed in, not held by anything in particular.

If you only have the tube in one head, there's a good chance that one of them was replaced. Early 1.7 heads didn't have the vents, and the late 2.0 ones don't have it either. Your pic looks like a 2.0 head, with only one stud in between the intakes instead of two.

--DD