(Beraisa): [The Shi'ur for drinking is] Melei Lugmo (singular).

What is the difference [from how we understood Melei Lugmav in our Mishnah? Melei Lugmo] is what one can fit in one cheek (if he moves it to one side).

(Beraisa): They said in the name of Beis Shamai that [one is liable only for] Melei Lugmav, which is a Revi'is.

Question (R. Chiyah bar Ada, to R. Mana): Why wasn't this taught among the leniencies of Beis Shamai and the stringencies of Beis Hillel?

Answer (R. Mana): It is due to Lugmo of Ben Avati'ach. It was more than a Revi'is.