Now as regards the validity of our assumption that relativity in age served as a means to determine privilege as to wedlock, proof can be furnished by certain nomenclatory features, as between members of a class or generation, to be found in the Malayan table in _Ancient Society_ and elsewhere. This will afford, incidentally, strong negative proof of our theory as to non-union between brother and sister. It will also incidentally furnish the strongest negative evidence that, so far from brother and sister living in incest, as Morgan holds, brother and sister were regarded as quite apart in the sense of any sexual relation between them. It will be seen that there is a profound distinction made in address between inter-marriageable people and those between whom celibacy is enjoined. Both Mr. Morgan and Mr. McLennan have drawn attention to the peculiarities in the terms of address as between ‘brothers’ and as between ‘sisters.’ It is curious that the full significance of the phenomena therein presented escaped two such keen intellects. We find here that terms of address as between persons of the same sex and of the same generation, and _ergo_ brothers or sisters, present the very remarkable features that (1) ‘The age of the person spoken to compared with that of the speaker plays a very important part in the matter of denomination.’ (2) ‘Such names refer not to the absolute age of the person addressed.’ (3) ‘The relationships of brother and sister are conceived in the twofold form of elder and younger, and not in the abstract, and there are special terms for each among the Seneca Iroquois.’ (4) ‘There is no name for brother and sister (Malayan system). On the other hand, there are a variety of names for use in salutations between “brother” and “sister” according to the age and sex of the person speaking in relation to the age and sex of the person addressed.’ (5) Among the Eskimo the form of the terms of relationship appears to depend, in some cases, more on the sex of the speaker than on that of the person to whom the term refers. (6) In Eastern Central Africa, if a man has a brother and a sister, he is called one thing by the brother, but quite a different thing by the sister. We will now illustrate the idea more completely by an extract of terms from the table of Hawaiian relationships in _Ancient Society_. An older or a younger brother is to a sister simply addressed or mentioned by the general term Kaiku nana, but to her, in address or mention of an older or a younger sister, they are respectively Kaik a’ana and Kaika-i-na. Again, an older or a younger sister is to a brother collectively Kaikuwaheena, but to him an elder or a younger brother is respectively Kaiknana and Kaikaina.