HOME LIFE 421 



man, and that they afford an example of rapid change of 

 specific form, owing to the ancestral species having been sub- 

 jected to a great change of conditions, both as regards climate 

 and food, and having had an immense area of new country 

 to roam over and multiply in, in every part of which they 

 would be subjected to different conditions. These considera- 

 tions, I think, fully meet the facts, and there ought to be no 

 large rodents found in the caves of Australia, and no other 

 rodents of very distinct type from those now living. When 

 any such are found it will be time enough to consider how 

 to account for them. It is, as you say, a most important fact 

 that, in three such distinct localities as New Zealand, Aus- 

 tralia, and Mauritius, no bones of extinct carnivora or other 

 mammalia should be found along with the wingless birds 

 and marsupials, while abundance of remains of these groups 

 are found. We may, I think, fairly claim this as a proof 

 that such placental mammals did not exist in those countries, 

 and the fact that the only exceptions in the existing Australian 

 fauna are mice indicates very clearly that they are a recent 

 introduction. When all the known facts are in our favour, 

 I do not think we need trouble ourselves to answer objections 

 and overcome difficulties that have not yet arisen, and prob- 

 ably never will arise." 



Some months later (November, 1867) he wrote me about 

 the dispersal and the colours of the races of man. On the 

 first point I replied at some length, principally to show why 

 we should not expect the primary regions which show the 

 great features of the distribution of birds, reptiles, and mam- 

 malia should also apply to man. On the question of colour 

 I replied as follows : " Why the colour of man is sometimes 

 constant over large areas while in other cases it varies, we 

 cannot certainly tell ; but we may well suppose it to be due 

 to its being more or less correlated with constitutional charac- 

 ters favourable to life. By far the most common colour of 

 man is a warm brown, not very different from that of the 

 American Indian. White and black are alike deviations from 

 this, and are probably correlated with mental or physical 



