which, like those of the land-birds and insects, might therefore have reached the islands ages ago. Moreover, with regard to mammals, even in cases where allied forms occur on either side of a sea-channel, it is found to be a general rule that if the channel is shallow, the species on either side of it are much more closely related than if it be deep--and this irrespective of its width. Therefore we can only conclude, in the words of Darwin--"As the amount of modification which animals of all kinds undergo partly depends on lapse of time, and as the islands which are separated from each other or from the mainland by shallow channels are more likely to have been continuously united within a recent period than islands separated by deeper channels, we can understand how it is that a relation exists between the depth of the sea separating two mammalian faunas, and the degree of their affinity--a relation which is quite inexplicable on the theory of independent acts of creation." * * * * * Looking to all these general principles of geographical distribution, and remembering the sundry points of smaller detail relating to oceanic islands which I will not wait to recapitulate, to my mind it seems that there is no escape from the following conclusion, with which I will bring my brief epitome of the evidence to a close. The conclusion to which, I submit, all the evidence leads is, that if the doctrine of special creation is taken to be true, then it must be further taken that the one and only principle which has been consistently followed in the geographical deposition of species, is that of so depositing them as to make it everywhere appear that they were not thus deposited at all, but came into existence where they now occur by way of genetic descent with perpetual migration and correlative modification. On no other principle, so far as I can see, would it be possible to account for the fact that "every species has come into existence coincident both in space and time with a pre-existing and closely allied species," together with the carefully graduated regard to physical barriers which the Creator must have displayed while depositing his newly formed species on either sides of them--everywhere making _degrees_ of structural affinity correspond to _degrees_ of geographical continuity, and _degrees_ of structural difference correspond to _degrees_ of geographical separation, whether by mountain-chains in the case of fresh-water faunas, by land and by deep sea in the case of marine faunas, or by reaches of ocean in the case of terrestrial faunas--stocking oceanic islands with an enormous profusion of peculiar species all allied to those on the nearest mainlands, yet everywhere avoiding the creation upon them of any amphibian or mammal, except an occasional bat. We are familiar with the doctrine that God is a God who hideth himself; here, however, it seems