ranged (good word to apply to slugs) from the groves of Cintra to the Cove of Cork.  But, as time rolled on, the cruel crawling sea rolled on also, and cut away all the western world from the foot of the Asturias to Macgillicuddy’s Reeks.  So the spotted slug continued to survive in two distinct and divided bodies, a large one in South-western Europe, and a small isolated colony, all alone by itself, around the Kerry mountains and the Lakes of Killarney.  At other times pure accident accounts for the presence of a particular species in the mainlands of Britain.  For example, the Bermuda grass-lily, a common American plant, is known in a wild state nowhere in Europe save at a place called Woodford, in county Galway.  Nobody ever planted it there; it has simply sprung up from some single seed, carried over, perhaps, on the feet of a bird, or cast ashore by the Gulf Stream on the hospitable coast of Western Ireland.  Yet there it has flourished and thriven ever since, a naturalised British subject of undoubted origin, without ever spreading to north or south above a few miles from its adopted habitat.

There are several of these unconscious American importations in various parts of Britain, some of them, no doubt, brought over with seed-corn or among the straw of packing-cases, but others unconnected in any way with human agency, and owing their presence here to natural causes.  That pretty little Yankee weed, the claytonia, now common in parts of Lancashire and Oxfordshire, first made its appearance amongst us, I believe, by its seeds being accidentally included with the sawdust in which Wenham Lake ice is packed for transport.  The Canadian river-weed is known first to have escaped from the botanical gardens at Cambridge, whence it spread rapidly through the congenial dykes and sluices of the fen country, and so into the entire navigable network of the Midland counties.  But there are other aliens of older settlement amongst us, aliens of American origin which nevertheless arrived in Britain, in all probability, long before Columbus ever set foot on the low basking sandbank of Cat Island.  Such is the jointed pond-sedge of the Hebrides, a water-weed found abundantly in the lakes and tarns of the Isle of Skye, Mull and Coll, and the west coast of Ireland, but occurring nowhere else throughout the whole expanse of Europe or Asia.  How did it get there?  Clearly its seeds were either washed by the waves or carried by birds, and thus deposited on the nearest European shores to America.  But if Mr. Alfred Russel Wallace had been alive in pre-Columban days (which, as Euclid remarks, is absurd), he would readily have inferred, from the frequent occurrence of such unknown plants along the western verge of Britain, that a great continent lay unexplored to the westward, and would promptly have proceeded to discover and annex it.  As Mr. Wallace was not yet born, however, Columbus took a mean advantage over him, and discovered it first by mere right of primogeniture.