These twins were united at the sacra by a cartilaginous or possibly osseous union.

They were exhibited in Paris in 1873, and provoked as much discussion there as in the United States.
Physically, Millie was the weaker, but had the stronger will and the dominating spirit.

They menstruated regularly from the age of thirteen.

One from long habit yielded instinctively to the other's movements, thus preserving the necessary harmony.

They ate separately, had distinct thoughts, and carried on distinct conversations at the same time.