NET
20 The sons of Merari by their families were Mahli and Mushi. These are the families of the Levites by their clans.
Darby
20 And the sons of Merari according to their families: Mahli and Mushi. These are the families of the Levites according to their fathers' houses.
KJV
20 And the sons of Merari by their families; Mahli, and Mushi. These [are] the families of the Levites according to the house of their fathers.