cal·var·i·um (kl-vâr-m)
n. pl. cal·var·i·ums or cal·var·i·a (--)
The upper domelike portion of the skull without the lower jaw or the lower jaw and the facial parts.
[Latin calvaria, skull, from calva, from calvus, bald.]
ref..http://www.thefreedictionary.com/calvarium