Descent groups and local groups are conceptually and empirically two quite different kinds of social entity, and no good can come of confusing one with the other. Because of all that, and because descent groups are self perpetuating and of indefinite duration, such groups are better suited to be also jural entities or jural collectivities than are groups for inclusion in which patrifiliation is merely necessary or merely sufficient. Among the Nuer, though, there is a kind of group for inclusion in which patrifiliation is the necessary and sufficient condition. The kind of group for inclusion in which patrifiliation is not necessary and sufficient but which does, according to Evans-Pritchard, center both normatively and normally on a small set of agnatically related men, is designated cieng in the Nuer language. In many African societies there is more than one kind of culturally constituted relation of patrifiliation.