I agree ^ ^ ^ but I'm also a bit concerned about the other dark areas between some scales nearby that are "in line" between some of the missing scales. I think a vet visit would be a good idea- this is not something you want to have spread to other scales. It doesn't look like what I've personally seen before, but hopefully a well-qualified herp vet would be of some help- along with some lab work, perhaps.Off-hand I'd say it's potentially fungal (it's somewhat similar to what I have seen)- but do see a vet.