In my _Geographical Distribution of Animals_, Vol. I., p. 357, I have given a somewhat different hypothetical explanation of the relations of Java and Borneo to the continent, in which I took account of changes of land and sea only; but a fuller consideration of the influence of changes of climate on the migration of animals, has led me to the much simpler, and, I think, more probable, explanation above given. The amount of the relationship between Java and Siam, as well as of that between Java and the Himalayas, is too small to be well accounted for by an independent geographical connection in which Borneo and Sumatra did not take part. It is, at the same time, too distinct and indisputable to be ignored; and a change of climate which should drive a portion of the Himalayan fauna southward, leaving a few species in Java and Borneo from which they could not return owing to the subsequent isolation of those islands by subsidence, seems {387} to be a cause exactly adapted to produce the kind and amount of affinity between these distant countries that actually exists. THE PHILIPPINE ISLANDS. A general account of the fauna of these islands, and of their biological relations to the countries which form the subject of this chapter, has been given in my _Geographical Distribution of Animals_, Vol. I. pp. 345-349; but since the publication of that work considerable additions have been made to their fauna, having the effect of somewhat diminishing their isolation from the other islands. Four genera have been added to the terrestrial mammalia--Crocidura, Felis, Pteromys, and Mus, as well as two additional squirrels; while the black ape (_Cynopithecus niger_) has been struck out as not inhabiting the Philippines. This brings the true land mammalia to twenty-one species, of which fourteen are peculiar to the islands; but to these we must add no less than thirty-three species of bats of which only ten are peculiar.[93] In these estimates the Palawan {388} group has been omitted as these islands contain so many Bornean species that if included they obscure the special features of the fauna.