This family has been associated usually, as a tribe, with the family Bembicidae, with which, however, according to my views, it has no relationship whatever. It is in reality much closer allied to the Nyssonidae, next to which I have placed it, and from which some of the species are separated with difficulty.The characters made use of in my table of families will, however, I think readily separate these three families, and it is unnecessary to repeat them here.