All the girls pretended to have met this supernatural being more or less often.

And those who laughed the loudest were not the most at ease.
When he did not show himself, he betrayed his presence or his passing by accident, comic or serious, for which the general superstition held him responsible.

Had any one met with a fall, or suffered a practical joke at the hands of one of the other girls, or lost a powderpuff, it was at once the fault of the ghost, of the Opera ghost.
After all, who had seen him?
You meet so many men in dress-clothes at the Opera who are not ghosts.

But this dress-suit had a peculiarity of its own.

It covered a skeleton.