you can click on the pic to make it larger. I don't see a black chicken. The three I do see sitting together in the pic I would say are all the same breed. Unfortunately, I don't know what breed that is.
Maybe they meant "back" one instead. They look like a Crele pattern, but as what breed, it is too hard to tell from the quality of the picture. Are they bantams or large fowl?
Well they do look like Cream Legbars which are an autosexing breed developed by Prof Punnett & others, at Cambridge. They are basically barred leghorn types. He'd split the blue gene from the pea comb & these have single combs, with crests, large blue eggs & inhibitor of gold.
I think it was Prof Punnett having fun.
But afaik they were not present in USA.
But Cream Legbars are supposed to have yellow legs & white earlobes.