My primary subject is totemism, and I have treated of exogamy for the most part only so far as it occurs in con junction with totemism; for the two institutions not only differ but overlap, each of them being sometimes found without the other. Tribes which are exogamous without being totemic do not properly fall within the scope of the book but I have noticed a few of them, such as the Todas in India and the Masai in Africa, either on the ground of their association with totemic tribes or because their social system presents some features of special interest. However.