I will begin with a brief history of the subject. So long as it was supposed that all the peoples of the world denoted relationship in the same way, namely, that which is customary among ourselves, there was no problem. There was no reason why the subject should have awakened any interest, and so far as I have been able to find, it is only since the discovery of the classificatory system of relationship that the problem now before us was ever raised. I imagine that, if students ever thought about the matter at all, it must have seemed obvious that the way in which they and the other known peoples of the world used terms of relationship was conditioned and determined by the social relations which the terms denoted. The state of affairs became very different as soon as it was known that many peoples of the world use terms of relationship in a manner, and according to rules, so widely different from our own that they seem to belong to an altogether different order, a difference well illustrated by the confusion which is apt to arise when we use English words in the translation of classificatory terms or classificatory terms as the equivalents of our own. The difficulty or impossibility of conforming to complete truth and reality, when we attempt this task, is the best witness to the fundamental difference between the two modes of denoting relationship. I do not know of any discovery in the whole range of science which can be more certainly put to the credit of one man than that of the classificatory system of relationship by Lewis Morgan. By this I mean, not merely that he was the first to point out clearly the existence of this mode of denoting relationship, but that it was he who collected the vast mass of material by which the essential characters of the system were demonstrated, and it was he who was the first to recognise the great theoretical importance of his new discovery. It is the denial of this importance by his contemporaries and successors which furnishes the best proof of the credit which is due to him for the discovery. The very extent of the material he collected[1] has probably done much to obstruct the recognition of the importance of his work. It is a somewhat discouraging thought that, if Morgan had been less industrious and had amassed a smaller collection of material which could have been embodied in a more available form, the value of his work would probably have been far more widely recognised than it is to-day. The volume of his material is, however, only a subsidiary factor in the process which has led to the neglect or rejection of the importance of Morgan’s discovery. The chief cause of the neglect is one for which Morgan must himself largely bear the blame. He was not content to demonstrate, as he might to some extent have done from his own material, the close connection between the terminology of the classificatory system of relationship and forms of social organisation. There can be little