The Attic helmet was a bronze cast job of earlier times, there's no problem with a later iron helmet having a superficial resemblance or perhaps being modeled on the Attic. Maybe there was a conscious effort to return to classic designs in an era dominated by Skythian armor.
Check the back cover for a reconstruction.
http://books.google.com/books?id=ccg...page&q&f=false
http://www.4shared.com/get/SgrtZoFM/...Infantrym.html