already prevails among the various specialists upon the most important of the land-bridges, although individuals cannot always “see the wood for the trees.”[1] We refer in this connection to the summary given in Chapter V of the views of twenty specialists on the several bridges, whether favourable or hostile. It is regarded as certain that there was a land connection, sometimes broken, between North America and Europe, which finally broke in the Glacial Period; a similar one between Africa and South America, which vanished in the Cretaceous Period; a third, the “Lemurian” bridge between Madagascar and India, which broke down at the beginning of the Tertiary; and finally a “Gondwana” bridge from Africa through Madagascar and India to Australia, which split up in the earliest Jurassic. Formerly also a land connection must have prevailed between South America and Australia, but the view that this was formed by a bridging-continent in the Southern Pacific is advocated by only a few workers. Most of them assume that this connection lay via Antarctica, since this lies on the shortest
- ↑ “Nevertheless there are still to-day some opponents of the land-bridges. Among them G. Pfeffer is especially prominent. He relies on the fact that many forms now confined to the southern hemisphere are found fossil in the northern. For him there is no doubt that they were once more or less universally distributed. This conclusion is not at all convincing; still less the further assumption that in all cases of a present discontinuous distribution in the south we ought to accept a former universal distribution, even though a fossil occurrence in the north has not been recorded. If he thus explains all peculiarities of distribution exclusively by wanderings between the northern continents and their mediterranean bridges, then this assumption rests entirely on unsafe foundations” (Arldt, “Südatlantische Beziehungen,” Peterm. Mitt., 62, pp. 41–46, 1916). That the affinities of the southern continents can be explained more simply and more completely by direct land connections than by parallel migrations from the common northern region, certainly needs no explanation, even if in isolated instances the process could have taken place in such a manner as Pfeffer assumes.
