We are here again confronted by a problem in distribution that does not differ in principle from ethnological problems relating to other phases of culture. A sharply individualized feature is found not like the Hawaiian principle practically within the limits of a single continuous area but in several diverse and remote regions of the globe. It is impossible to hold with Morgan that the similarity found is an index of racial affinity unless we are willing to assume that the Indians of the eastern United States are not related at all to those west of the Rocky Mountains. The principle of diffusion obviously accounts for much. No one would hesitate to assume that the Singhalese and Vedda systems are connected and we should willingly regard both as historically related to the nomenclature of southern India. We might even be willing to grant that the Melanesian and Australian variants of the Dakota principle had the same source of origin. But how can we explain the predominance of the identical principle precisely in the eastern regions of North America and its absence in a great part of the Far West? And how can we account for the African approximations to the same pattern? We seem to have an independent evolution of the same highly characteristic trait in at least three distinct areas. Must we content ourselves with simply accepting the data as irreducible ethnological phenomena or can we carry our analysis a step further? That the inclusiveness of terms which strikes us in the systems sharing the Dakota principle is somehow connected with the social divisions of the tribes concerned has been repeatedly noted. Even in his earlier, purely descriptive work Morgan remarked that among the Iroquois clan members were brothers and sisters as if children of the same mother.[35] Similarly among the Tlingit we are told that a single word is applied to the mother’s sister and all other women of the same moiety and generation.[36] The Yakut apply one term to any woman older than the speaker and belonging to the same gens.[37] Such instances might easily be multiplied. It is therefore rather natural to look to a clan or gentile system for the explanation of the ‘classificatory feature’, _i.e._, of bifurcate merging.