With a custom so deeply ingrained as incest would be in the nature of man’s ancestor, still doubtless vastly animal, we may indeed surmise that the process of its decay was long and tedious. The temptation, as we have said, to such easy procuration of a mate in comparison with the danger and comparatively scanty results of capture, was very great, whilst the continual propinquity of father and daughter would tend to constant recrudescence, especially in default of any trace of law against it. There must, then, evidently have been a transition era of vast durance, between the type of the isolated consanguine group whose only resource in matrimony was exogamic hostile capture, as the outcome of the incestuous lust of its solitary male head, and the all-embracing tribe composed of an aggregation of several groups, and possessing thus _ipso facto_ all the necessary elements of an endogamic connubium quite incompatible with such incest. In such a tribe, a group of women in many cases formed the pivotal centre, and capture was often found only as a form in survival. Is it possible to retrace the main features of an epoch of such evident importance in social evolution? In view of the fact that, in the past course of our argument, such law as would seemingly have been necessarily evolved in regulation of each step in primitive progress has been found identical in form with some actual savage custom, may not a deeper investigation of savage custom disclose further co-ordination, and prove equally fertile in interpretation of the past? Whilst, again, many obscure observances in actual lower life, in consonance with such archaic genesis, may take a rational form, though the origin seems apparently lost for ever. Such research will, I think, clearly show that many social features in modern savage habit afford internal evidence that, as a fact, they could only have arisen in such a transition era. They also bear marks of a very lengthened evolutionary process, and thus confirm the natural idea of a halt of portentous length at the threshold of the present haven of comparative social rest. We shall doubtless find that the door left ajar by the entrance of the outside suitor was not to yield further with ease to the pressure of new needs, half-hearted as men would be, from the conservative force of old ideas, of incest and entire masculine dominance.