To begin with, there must have existed hordes, which, though doubtless human, were still very bestial as regards their instincts and intelligence. In these hordes, which were not very numerous, the women being taken possession of by the most robust old males, the young ones were obliged either to quit the group or to remain in it by ravishing one or two women from rival hordes; for exogamy was a necessity. The least advanced of the Australian tribes seem to be still in this primitive stage. At length a little order was put into this disorder by the horde breaking up into clans; it was then decided that all the men and all the women of each clan should be brothers and sisters, and should not intermarry, and that on the other hand, all the men of a clan should be the husbands of all the women of the neighbouring clan, simply by right of birth. The Kamilaroi of Australia may represent the second stage. In Polynesia the principle is the same, but the idea has become restricted and defined. Groups of real brothers marry groups of women actually sisters, thus forming households at once polyandric and polygamic; but traces of the antique marriage by fictitious groups of brothers and sisters appear again in the terms used to designate the various degrees of kinship. These terms are in reality purely classificatory, and take little account of real consanguinity. Among the Redskins a new and important restriction has been established. Marriage outside the clan is continued, but not marriage by groups of sisters and brothers. That this was done in primitive times, however, is proved by the familial vocabulary. On the other hand, they have clearly renounced polyandry, and adopted polygamy with not less clearness; but this polygamy is special, and it is generally a group of sisters who marry the polygamous husband. As for the terms of kinship, they are always general and classificatory. The relations are denominated by groups, and the titles of kinship do not in the least correspond to the ties of blood. Lastly, among certain nomad Mongols of Asia, the strict prohibition to marry within the clan, and the terms of kinship applying to groups, show that formerly a familial system, analogous to that of the American Redskins, has been in use. Moreover, this classificatory system is preserved entire in the denominations of kinship by the Tamils of India. But among these last, and also among certain Mongol populations of Thibetan Himalaya, the primitive family, at once polygamic and polyandric, that of the Hawaian islanders, has evolved after its own manner, which it is interesting to notice.