After their kind, i.e. according to their several kinds. They shall come unto thee of their own accord, by my impulse, or by the conduct of angels, as Genesis 2:19.
Related Commentaries of Genesis 6:20
Genesis 6:20
20 Of fowls after their kind, and of cattle after their kind, of every creeping thing of the earth after his kind, two of every sort shall come unto thee, to keep them alive.