Mills brothers were 4 - one died and they went for a short while with 3 then their father (?) stepped in and they had 4 again then he oranother one passed on - they held on as 3 for a while but they were all pretty old by then their hayday was in theri early days I still love to hear them. Ames brothers I don't remember but the Ink Spots I love also they were 4. One time I heard beautiful music coming from a car getting gas in a gas station and it was the Ink Spots - quite a crowd gathered and wouldn't let them go for a while but they obviously enjoyed it. Female voices don't have the range of male voices ( except for Yma Sumac - anyone remember her ) so don't lend to the type of harmony in male quartets. Bob Anibal