_Remarks on the General Character of the Fauna of Japan._--From a general view of the phenomena of distribution we feel justified in placing Japan in the Palæarctic region; although some tropical groups, especially of reptiles and insects, have largely occupied its southern portions; and these same groups have in many cases spread into Northern China, beyond the {231}usual dividing line of the Palæarctic and Oriental regions. The causes of such a phenomenon are not difficult to conceive. Even now, that portion of the Palæarctic region between Western Asia and Japan is, for the most part, a bleak and inhospitable region, abounding in desert plateaus, and with a rigorous climate even in its most favoured districts, and can, therefore, support but a scanty population of snakes, and of such groups of insects as require flowers, forests, or a considerable period of warm summer weather; and it is precisely these which are represented in Japan and North China by tropical forms. We must also consider, that during the Glacial epoch this whole region would have become still less productive, and that, as the southern limit of the ice retired northward, it would be followed up by many tropical forms along with such as had been driven south by its advance, and had survived to return to their northern homes. It is also evident that Japan has a more equable and probably moister climate than the opposite shores of China, and has also a very different geological character, being rocky and broken, often volcanic, and supporting a rich, varied, and peculiar vegetation. It would thus be well adapted to support all the more hardy denizens of the tropics which might at various times reach it, while it might not be so well adapted for the more boreal forms from Mongolia or Siberia. The fact that a mixture of such forms occurs there, is then, little to be wondered at, but we may rather marvel that they are not more predominant, and that even in the extreme south, the most abundant forms of mammal, bird, and insect, are modifications of familiar Palæarctic types. The fact clearly indicates that the former land connections of Japan with the continent have been in a northerly rather than in a southerly direction, and that the tropical immigrants have had difficulties to contend with, and have found the land already fairly stocked with northern aborigines in almost every class and order of animals.