Rav Mari from Nahar Pakod became head [in Sura, and so too Rash"b Yuchsin says he was head of the yeshiva in Sura (Yuchsin in the order of tradition from the Rama"n says Pumbedita)] in year 4508 and ruled for 8 years. [And in Shada"k page 36b he died in year 4522, and in page 58b Rav Mari was in Pumbedita and Rav Yehuda was in Mata Mechasia as in year 4500.] Rav Acha ruled after him for half a year [(Tzemach David)].