Constantine II, as Caesar, 316-337. Follis (Bronze, 19 mm, 2.53 g, 12 h), Rome, 317. CONSTANTINVS IVN NOB CAES Bare-headed, draped and cuirassed bust of Constantine II to right, seen from behind. Rev. PRINCIPIA I-VVENTVTIS / A / R S Mars standing front, head to right, holding inverted spear in his right hand and placing his left on shield set on ground. RIC 91. Extremely rare, apparently the second known example. A lovely example, very well struck and perfectly centered. Very minor weakness, otherwise, about extremely fine.