If we cannot give more than this general interpretation of the reciprocal feature as found in North America, we can on the other hand show quite definitely that its occurrence is a function of geographical position there. The practical absence of this trait in the immense region particularly dealt with by Morgan is as remarkable as its spread over a practically continuous region in the Far West, among the Lillooet, Spokane, Kootenai, Nez Percé, Wishram, Takelma, and various Californian and Shoshonean Plateau populations, as well as in a considerable number of Southwestern tribes. The Pacific, Plateau and Southwestern regions obviously define the distribution of reciprocity in North America, which thus becomes intelligible only through diffusion. _Various Features._ The principles of kinship nomenclature that have been treated hitherto are far from exhausting the variety found in a survey of the world. A very odd mode of addressing relatives after presentation of a gift has been mentioned for the Masai (p. 104), and there is little doubt that more extensive knowledge will reveal equally quaint notions elsewhere. Here I merely wish to enumerate a few examples from the particular point of view assumed in this chapter. It is a remarkable fact that while in Australia the principle of bifurcation is consistently carried to the grandparental stratum of society in conjunction with the reciprocal feature, the North American region in which the Dakota principle is especially prominent lacks the distinction between mother’s and father’s parents, so that Morgan does not even dedicate special columns to these relationships in his elaborate schedules and notes the discrimination with some surprise for the Spokane.[57] This feature is nevertheless widely spread in the Far West, coinciding to some extent with that of reciprocity. We find it among Salish and Shoshonean tribes, in California, among the Takelma and Wishram, and to some extent in the Southwest. Both the positive and the negative facts of distribution indicate the occurrence of diffusion.