be regarded as exceedingly strong evidence against the former or at least ancient existence of exogamous groups. _Supposed Features of ‘Classificatory’ Systems._ Under the misnomer ‘classificatory systems’ some writers have included consideration of the principle of differentiating elder and younger brothers and sisters. The distribution of this distinction is simply staggering when one attempts to trace it more or less systematically. Of North American systems, I can offhand recall only two, the Pawnee and Kiowa, in which it does not appear. We find it in association with the Hungarian and Chukchee terminologies, both of which lack the Dakota principle, and it occurs with the Hawaiian no less than the vast majority of bifurcate systems. So far as I know, the only one who has offered any explanation of the phenomenon is Dr. Rivers, who once connected it with a difference in the time of tribal initiation.[55] But since there are many peoples, _e. g._, in North America, who do not practise any form of tribal initiation, the hypothesis hardly seems tenable and we must rest content to accept the facts of distribution. Another feature that is often erroneously treated in association with the Dakota principle is that of reciprocity, which has already been referred to as the usage of designating a pair of relatives, more particularly two belonging to different generations, by a single term. Thus, the Shoshone call the mother’s father and the daughter’s son (man speaking) by one term. Such usage would be manifestly opposed to the Hawaiian principle with which it does not seem to be associated. It is found in connection with the Dakota scheme in Melanesia and particularly in Australia, but is markedly absent from the merging systems of North America. Since here it is highly developed where the Dakota principle does _not_ occur, it cannot be regarded as an essential element of ‘classificatory systems’. The question remains how we are to account for the facts of distribution. Australian data forcibly suggest that, there at least, the reciprocal feature is a reflection of social organization. Grandparents and grandchildren, by the curious rule of descent that regulates affiliation with the matrimonial classes of the area, are necessarily in the same class, _i.e._, a father’s father and a son’s son or a mother’s father and a daughter’s son (man speaking) are fellow-members of a class. The fit seems too close to admit of an accidental association. But when we turn to the North American region of reciprocal features the interpretation no longer holds since no vestige is found there of any institution that might align the relatives under discussion in a common group. The inference is that there has been convergent development, and perhaps the most plausible explanation of the North American terms is that they are designations not so much of the relatives as of the relationship itself.[56]