i see the difference now.the black on the belly has very few breaks in it
It is more that you get the great checkering pattern, that breaks into the side pattern where you get the white flames. And the busy checks run in the two strips down each side.
But the clean pattern inbetween tends to contrast it... and you cannot really see it, but you will get yellow belly scales as well.. and other they are not consistent... so you get a few here and there.
But they were named yellow bellies for the yellow in their sides, not on their bellies... which always strikes me as a bit odd in that the yellow on the belly is so distinct... and they are named... well yellow bellies.