These phratries and classes regulate marriage.  It is forbidden to marry within one’s own phratry.  This custom is termed exogamy.  When the husband removes and lives in his wife’s group the marriage is matrilocal; if the wife removes it is patrilocal.

In addition to the division into classes each phratry is further divided into a number of totem kins.  A totem is usually a species of animals or plants; a body of human beings stands in a certain peculiar relation to the totem species and is termed the totem kin; each member of a totem kin is termed a kinsman.  Membership of the totem kin usually descends directly from parent to child.

The existence of these kinship organisations is universally recognised.  Mr R.H.  Mathews has recently asserted the existence of yet another form and at the same time controverted the accepted views as to the operation and meaning of those described above.  He distinguishes in certain tribes of New South Wales kinship organisations running across the phratries; these are of two kinds, according to the author, but they do not seem to differ in function.  They are termed by Mr Mathews “blood” and “shade” divisions, and are held by him to be the names of the really exogamous groups.  The subject is discussed in detail below.

In order to make the working of these regulations plain, let us take as an example the Kamilaroi tribe of N.S.  Wales, with two phratries, four classes and various totem kins.  The phratries are named Dilbi and Kupathin; Dilbi is divided into two classes, Muri and Kubi; Kupathin into Kumbo and Ipai.  The Dilbi totems, which may belong to either of the classes, are kangaroo, opossum and iguana; those of Kupathin are emu, bandicoot and black snake.  Every member of the tribe has his own phratry, class and totem; these all come to him by descent.

We have little or no information as to the local grouping of the Kamilaroi tribes, but it was possibly not unlike that of some of the tribes to the north-west.  In the case of the latter the tribal area was some 3000 sq. miles in extent, it was split up into smaller areas, thirty or more in number, which were the property of the local groups; a local group consisted frequently of three generations of relatives.  When we come to deal below with marriage regulations it will be shown that husband, wife and child under the four-class system all belong to different classes; there were therefore in each group at least three classes, if not four, and consequently members of two phratries.  If we assume that the same conditions prevailed among the Kamilaroi, the local groups would then be made up of members of both the Dilbi and Kupathin phratries; and probably all four classes, Muri, Kubi, Ipai and Kumbo, would be found in each group, which in Australia varied in size according to local conditions from 20 or 30 to 200; under special conditions, such as prevailed in the neighbourhood of Lake Alexandrina, the number might run up to 600 or more, but this was exceptional.