What are calistus?

Some articles on calistus:

Kelly Pool - Origins
... is provided in a November 10, 1916 Indianapolis Star obituary for one Calistus Mulvaney, who is listed as having died the preceding day ... He was widely known as the father of 'Kelly pool' and better known as Kelly Mulvaney than Calistus ... at Fox Lake Wis sixty-five years ago." In Calistus Mulvaney's entry in the 1910 United States Census (pictured at right), his occupation is listed as "billiard hall emp" and his position there as "keeper" ...