It has been difficult to trace the line of descendants of this founder of Prairie du Rocher. In a document of December 30, 1740, we learn that the late Ettienne Langlois married Catherine Beaudrau, a widow, and had the following children; Marie Louise, who married Pierre Messenger; Marie Josefine, m. Louis Populus sieur de St. Photes; Toinette, m. Pierre Boucher de Monbrum sieur de Soudray; Francois, Louis, Girard, Perine and Auguste. These last five were minors. From other sources it is learned that Ettienne had two brothers, August who lived at Kaskaskia, and Louis. What relation the notary Pierre Langlois was to these is not apparent. He was married to Catherine Normand Labriere, and had two children, Pierre and Marie Louise. The latter signed a marriage contract with Pierre Lefebhve of Vincennes, October 9, 1785. Pierre Langlois died in 1789, and his widow took oath to the inventory of the property December 14, of that year.