In these inquiries a great source of confusion arises (as all students must be aware) from the absence of exact terminology, of technical terms with a definite and recognised meaning. Thus when my friend, the late Mr. John Fergus McLennan, introduced the word ‘Exogamy,’ in ‘Primitive Marriage’ (1865), he probably knew perfectly well what he meant. But he did not then, from lack of practice in an inquiry practically novel, and originated by himself, express his meaning with exactness. He at first spoke of exogamy as the rule ‘which prohibited marriage within the tribe.’[16] But the word ‘tribe’ was later taken by Mr. McLennan to mean, and is now used as meaning, what cannot be a primitive community, a local aggregate of groups amicably occupying a considerable area of country; say the Urabunna tribe of Central Australia. Mr. McLennan did not wish to say that exogamy forbids an Urabunna tribesman to marry an Urabunna tribeswoman; he meant that exogamy prohibited marriage within the recognised kindred--that is, in this case, between members of totem kindreds of the same name, say Emu or Kangaroo. This fact he later made perfectly clear. But meanwhile such terms as ‘horde,’ ‘tribe,’ ‘sub-tribe,’ ‘family,’ ‘gens,’ ‘section,’ ‘phratria,’ ‘clan,’ many of them derived from civilised classical or Celtic usage, have been tossed up and down, in company with ‘class,’ ‘division,’ ‘section,’ and so on, in a way most confusing.[17] Odd new terms come from America, such as ‘socialry,’ ‘tutelaries,’ ‘ocular consanguinity,’ ‘ethnogamy,’ ‘conjugal conation,’ and so forth.[18] Most perplexing it is to find words like clan, family, tribe, _gens_, phratry, words peculiar to civilised peoples, Greek, Roman, or Celtic, applied to the society of savages. ‘The term “clan” implies descent in the female line,’ says the late Mr. Dorsey, following Major Powell; but why take the Celtic term ‘clan,’ which has no such signification, and confer it on what is really a totem kindred with descent in the female line?[19] Next, ‘several of the Siouan tribes are divided into two, and one into three sub-tribes. Other tribes are composed of phratries, and each sub-tribe or, phratry comprises a number of _gentes_.’ Is there a distinction between the ‘sub-tribes’ of some tribes, and the ‘phratries’ of others, or not? Apparently there is not, but the method of nomenclature is most confusing. I shall understand the terms which I employ, as follows: