We do not, perhaps, know any exogamous tribes in our sense of ‘tribe;’ a Dieri is not obliged to marry out of the Dieri, or an Urabunna out of the Urabunna. By ‘tribe’ here, it seems probable that Lord Avebury intends not a large local aggregate, but ‘a very small community,’ for he writes ‘we have seen that, under the custom of communal marriage, a child was regarded as related to the _tribe_, but not specially to any particular father or mother. Such a ‘state of things, indeed, is only possible in very small communities.’ Now a tribe is a very large community. The members of such communities must have been poor observers if they did not discover the relation between a child and the woman who bore and, for several years, nursed it. But such ‘tribes’ are not tribes in the sense in which I use the word; they are rather ‘groups of the same hearth.’ Now it is easy to see how small groups of the same hearth became exogamous, namely through sexual jealousy, and sexual tabu, which would oblige the young males to wander away, or to get wives by capture, practices resulting, under the tabu, in the sacred rule of exogamy. This, however, is not Lord Avebury’s theory of the origin of exogamy. Lord Avebury’s theory does not become more distinct when he says, ‘In Australia, where the same family names’ (totem names?) ‘are common almost over the whole continent, no man may marry a woman whose family name’ (totem name?) ‘is the same as his own’ (here the Arunta are an exception) ‘and who belongs therefore to the same tribe’ (p. 144). But surely, if the ‘family names’ are ‘common almost over the whole continent,’ a woman may well have the same ‘family name’ (say Emu) as a man, and yet need not be of his tribe. An Arunta Emu man and a Dieri Emu woman would have the same ‘family name’ (totem name), but would not, therefore, ‘belong to the same tribe.’ It even appears that Lord Avebury regards ‘tribe’ and ‘clan’ and ‘family’ as synonymous terms, for, in proof of the statement that people of the same ‘family name’ necessarily belong to the same ‘tribe,’ he quotes my late uncle, Mr. Gideon Scott Lang, ‘No man can marry a woman of the same clan, though the parties be no way related according to our ideas.’[3] By ‘clan’ Mr. Lang here meant totem kin, and if Lord Avebury thinks ‘clan’ equivalent to ‘tribe,’ a ‘tribe’ must be a totem kin, which it is not; at least if we understand ‘tribe’ as a local aggregate of various totem kindreds.