the wife's mother the same as the daughter; the wife's brother the same as the daughter's son. The

only conclusion I was then able to formulate was that these features were the result of some social institution resembling the matrimonial classes of Australia, which would have the effect of putting persons of alternate generations into one social category.

This idea was supported by the system of relationship of the Dieri of Australia which possesses at least one feature similar to those of Pentecost, a fact I happened to remember at the time because Mr. N. W. Thomas^[1] had used it as the basis of a reductio ad absurdum argument to show that terms of relationship do not express kinship. The interest of the Pentecost system seemed at first to lie in the possibility thus opened of bringing Melanesian into relation with Australian sociology, a hope which was the more promising in that the people of Pentecost and the Dieri resemble one another in the general character of their social organisation, each being organised on the dual basis with matrilineal descent. When in Pentecost, however, I was unable to get further than this, and the details of the system remained wholly inexplicable.

The meaning of some of the peculiarities of the Pentecost system became clear when I reached the Banks Islands; they were of the same kind as

1. ↑ Kinship Organisations and Group Marriage in Australia, Cambridge, 1906, p. 123.