John Gill Commentary Genesis 7:8

"Of clean beasts, and of beasts that are not clean, and of birds, and of everything that creepeth upon the ground," — Genesis 7:8 (ASV)

Of clean beasts, and of beasts that are not clean Seven couple of the one, and a couple of the other: and of fowls , clean and unclean, also a like number: and of everything that creeps upon the earth ; and upon that only, not in the water, for these has no need of the ark, they could live in the waters.