There's a saxophone and a drummer with a full kit, and the caller is singing the calls. Some new contra syncretism? Or just a typical night in 1955?

The singing square, "Just Because," from live recordings over the years:

1952	Frank Fortune (studio)
1955	Frank Fortune
1973	Glenn Pease
2008	David Millstone (youtube)
2011	Tod Whittemore (youtube)
2011	Walter Lenk

(If you compare a dance program from 1955 or 1965 to one now, the biggest thing you notice is half the dances were singing squares, and the ones that weren't were mostly couple dances.)

Update 2012-01-22: I later transcribed the 'Just Because' recordings.

Update 2012-02-29: I tried my hand calling this yesterday and wrote about it after.