Much light has been thrown on this curious problem since our return, by an American naturalist, Mr. Bland, in a paper read before the American Philosophical Society, on ’The Geology and Physical Geography of the West Indies, with reference to the distribution of Mollusca.’  It is plain that of all animals, land-shells and reptiles give the surest tokens of any former connection of islands, being neither able to swim nor fly from one to another, and very unlikely to be carried by birds or currents.  Judging, therefore, as he has a right to do, by the similarity of the land-shells, Mr. Bland is of opinion that Porto Rico, the Virgins, and the Anguilla group once formed continuous dry land, connected with Cuba, the Bahamas, and Hayti; and that their shell-fauna is of a Mexican and Central American type.  The shell-fauna of the islands to the south, on the contrary, from Barbuda and St. Kitts down to Trinidad, is South American:  but of two types, one Venezuelan, the other Guianan.  It seems, from Mr. Bland’s researches, that there must have existed once not merely an extension of the North American Continent south-eastward, but that very extension of the South American Continent northward, at which I have hinted more than once in these pages.  Moreover—­a fact which I certainly did not expect—­ the western side of this supposed land, namely, Trinidad, Tobago, Grenada, the Grenadines, St. Vincent, and St. Lucia, have, as far as land-shells are concerned, a Venezuelan fauna; while the eastern side of it, namely, Barbadoes, Martinique, Dominica, Guadaloupe, Antigua, etc., have, most strangely, the fauna of Guiana.

If this be so, a glance at the map will show the vast destruction of tropic land during almost the very latest geological epoch; and show, too, how little, in the present imperfect state of our knowledge, we ought to dare any speculations as to the absence of man, as well as of other creatures, on those great lands now destroyed.  For, to supply the dry land which Mr. Bland’s theory needs, we shall have to conceive a junction, reaching over at least five degrees of latitude, between the north of British Guiana and Barbadoes; and may freely indulge in the dream that the waters of the Orinoco, when they ran over the lowlands of Trinidad, passed east of Tobago; then northward between Barbadoes and St. Lucia; then turned westward between the latter island and Martinique; and that the mighty estuary formed—­for a great part at least of that line—­ the original barrier which kept the land-shells of Venezuela apart from those of Guiana.  A ‘stretch of the imagination,’ doubtless:  but no greater stretch than will be required by any explanation of the facts whatsoever.

And so, thanking Mr. Bland heartily for his valuable contribution to the infant science of Bio-Geology—­I take leave, in these pages at least, of the Earthly Paradise.