The Collaborative International Dictionary of English v.0.48:
Seriatim \Se`ri*a"tim\, adv. [NL.] In regular order; one after the other; severally. [1913 Webster]WordNet (r) 3.0 (2006):
seriatim adv 1: in a series; one after anotherBouvier's Law Dictionary, Revised 6th Ed (1856):
SERIATIM. In a series, severally; as, the judges delivered their opinions seriatim.