It is just the same with all the other animals and plants that now inhabit these isles of Britain. If there be anything at all with a claim to be considered really indigenous, it is the Scotch ptarmigan and the Alpine hare, the northern holygrass and the mountain flowers of the Highland summits. All the rest are sojourners and wayfarers, brought across as casuals, like the gipsies and the Oriental plane, at various times to the United Kingdom, some of them recently, some of them long ago, but not one of them (it seems), except the oyster, a true native. The common brown rat, for instance, as everybody knows, came over, not, it is true, with William the Conqueror, but with the Hanoverian dynasty and King George I. of blessed memory. The familiar cockroach, or 'black beetle,' of our lower regions, is an Oriental importation of the last century. The hum of the mosquito is now just beginning to be heard in the land, especially in some big London hotels. The Colorado beetle is hourly expected by Cunard steamer. The Canadian roadside erigeron is well established already in the remoter suburbs; the phylloxera battens on our hothouse vines; the American river-weed stops the navigation on our principal canals. The Ganges and the Mississippi have long since flooded the tawny Thames, as Juvenal's cynical friend declared the Syrian Orontes had flooded the Tiber. And what has thus been going on slowly within the memory of the last few generations has been going on constantly from time immemorial, and peopling Britain in all its parts with its now existing fauna and flora.