Almost all the animals as yet mentioned are gregarious, and the males must frequently pair with their own daughters, for they expel the young males as well as all intruders, until forced by old age and loss of strength to yield to some stronger male. It is therefore not improbable that gregarious animals may have been rendered less susceptible than non-social species to the evil consequences of close interbreeding, so that they may be enabled to live in herds without injury to their offspring. Unfortunately we do not know whether an animal like the cat, which is not gregarious, would suffer from close interbreeding in a greater degree than our other domesticated animals. But the pig is not, as far as I can discover, strictly gregarious, and we have seen that it appears eminently liable to the evil effects of close interbreeding. Mr. Huth, in the case of the pig, attributes (page 285) these effects to their having been "cultivated most for their fat," or to the selected individuals having had a weak constitution; but we must remember that it is great breeders who have brought forward the above cases, and who are far more familiar than ordinary men can be, with the causes which are likely to interfere with the fertility of their animals. The effects of close interbreeding in the case of man is a difficult subject, on which I will say but little. It has been discussed by various authors under many points of view. (17/25. Dr. Dally has published an excellent article (translated in the 'Anthropolog. Review' May 1864 page 65), criticising all writers who have maintained that evil follows from consanguineous marriages. No doubt on this side of the question many advocates have injured their cause by inaccuracies: thus it has been stated (Devay 'Du Danger des Mariages' etc. 1862 page 141) that the marriages of cousins have been prohibited by the legislature of Ohio; but I have been assured, in answer to inquiries made in the United States, that this statement is a mere fable.) Mr. Tylor (17/26. See his interesting work on the 'Early History of Man' 1865 chapter 10.) has shown that with widely different races in the most distant quarters of the world, marriages between relations--even between distant relations--have been strictly prohibited. There are, however, many exceptions to the rule, which are fully given by Mr. Huth (17/27. 'The Marriage of Near Kin' 1875. The evidence given by Mr. Huth would, I think, have been even more valuable than it is on this and some other points, if he had referred solely to the works of men who had long resided in each country referred to, and who showed that they possessed judgment and caution. See also Mr. W. Adam 'On Consanguinity in Marriage' in the 'Fortnightly Review' 1865 page 710. Also Hofacker 'Ueber die Eigenschaften' etc. 1828.) It is a curious problem how these prohibitions arose during early and barbarous times. Mr. Tylor is inclined to attribute