We are, of course, confronted by the difficulty that this evidence may simply disclose the lines along which tribal intercommunication has been most easy, whether in the way of simple interchange of commodities, evidence of which we have over considerable areas in Australia, or in the way of intermarriage, which, as we see by the example of the Urabunna and the Arunta, is found in spite of fundamental differences of tribal organisation. A common stock of folktales due to this cause would leave unexplained the prominence of the bird myth in the sacred rites, and leave the present hypothesis, in this regard, on a par with that of post-phratriac dissemination, in respect of probability. On the other hand we have the Scylla of tribal property in land, an idea so firmly rooted in our own day in the minds of the Australians as to make wars of conquest unthinkable to them, and to transform the practical part of their intertribal feuds into mere raids. If, therefore, investigation showed that the central and eastern tribes are in possession of a stock of folktales with many items in common, we should always have to take into consideration the possibility that these tales antedate the complete occupation of Australia, and go back to a period when the eastern and central divisions were in close relation. The probability of this view would, of course, depend on the extent of the resemblance between the two stocks of tales, or, perhaps, rather on the extent of the resemblance between those tales which they have in common; for it is clear that a close resemblance between comparatively few items would be more effective proof of intercommunication than a less marked general resemblance between the tale-stocks as a whole.