not an arbitrary rule of classification but a definite rationale. However, it is worth noting that while the moiety theory explains a number of traits better and more simply than the hypothesis of multiple clans or gentes of which it is a special form, the latter is not in so bad a plight as Morgan would have us believe. That I should call my father’s brothers and male cousins of the paternal line ‘father’ and my mother’s sisters and female cousins of the female line ‘mother’, follows from the general hypothesis of exogamy no less than from the moiety theory. The difficulty urged is the grouping together of brothers’ sons who are not clansmen under a matrilineal organization with sisters’ sons who are. But all terms of relationship are correlative: the concept of elder brother is meaningless without the correlated concept of younger brother; so the very fact that I address my father’s brother as ‘father’ has as a necessary consequence that he should address me as ‘son’ regardless of whether his own son is in my clan. Similarly, the fact that my father’s brother’s son and I both address my own father as father makes us brothers irrespective of clan affiliation. Clan affiliation is still the primary determinant since it fixes the connotation of the word translated ‘father’, while the other usages mentioned are derivative applications. The objection that naturally obtrudes itself is why the term for father should be taken as the starting-point rather than that for son or brother. The answer lies in the fact that in a number of instances the term for father has an emphatically clan or gentile significance, being extended even to father’s clansmen of the speaker’s generation, as among the Crow and Arizona Tewa. Nevertheless, it cannot be denied that from the point of view of summarizing the data comprised under the caption of ‘Dakota principle’ or intimately linked with them the moiety theory is distinctly superior. Thus, the union of father’s sister’s husband and mother’s brother under a single head does not follow from a multiple clan or gentile organization but is intelligible on the basis of a dual division. The weakness of the moiety theory lies in another direction. In order that the dual organization may fashion kinship nomenclature, it must of course exist. Now it does occur in Australia and Melanesia, though not universally, and in part of North America, but it is lacking in many regions of this continent and, so far as I know, in Africa. If we derive the Dakota principle exclusively from the dual organization we are therefore obliged to assume either that this institution once had a far wider range of distribution or that the nomenclature it produced traveled independently of the moieties to a considerable number of other peoples. This is a difficulty that must be frankly recognized.