Lombock Strait, a narrow neck of water between Bali and Lombock Island, and Macassar Strait, separating Celebes from Borneo, are parts of a continuous passage of water which in remote times separated two continents—an Indo-Malayan continent to which belonged Borneo, Sumatra, Java, and the Malay Peninsula; and an Austro-Malayan continent, now represented by Australia, Celebes, the Moluccas, New Guinea, Solomon’s Islands, etc. Wallace first announced this ancient boundary, and it has been called ‘Wallace’s line.’ He was led to infer its existence by the fact which he observed as he travelled about from island to island, that, while the faunas of these two regions are as wholes very different from each other, the faunas of the various land patches in each area have a wonderful similarity. Australia is a veritable museum of old and obsolete forms of both plants and animals. Its fauna and flora are made up prevailingly of forms such as have on the other continents long been superseded by more specialised species. No true mammals, excepting men and a few rats, lived in Australia when Englishmen first went there. The most powerful animals were the comparatively helpless marsupials. The explanation of these remarkable facts is probably this: The Australian continent, which formerly included New Guinea and other islands to the north, has not been connected with the other land masses for a very long period of time. The development upon the other continents of the more powerful mammals, especially of the ungulates and the carnivora, resulted in the extermination of the more helpless forms from most of the earth’s surface. But Australia, protected by its isolation, has retained to this day its old-fashioned forms of life, neither land animals nor plants having been able to navigate the intervening straits. This supposition is strengthened by the fact that fossil remains of marsupials are to-day found scattered all over the world, while, with the exception of the American opossums, living marsupials are found only in Australia and its islands. There is to-day not a single survivor of these once-numerous races in either Europe, Asia, or Africa. Similar facts of distribution are furnished by the lemurs—those small, monkey-like animals with fox faces, which are sometimes called ‘half-apes,’ since they are supposed to be the link connecting the true apes with lower forms. Fossil lemurs are found in both America and Europe, but lemurs are now extinct in both continents. Those of America were probably exterminated by the carnivora, who are known to be very fond of monkey meat of all kinds. The European lemurs seem to have migrated southward into eastern Africa at a time when Madagascar formed a part of the mainland. ‘There they have been isolated, and have developed in a fashion comparable to that which has occurred in the case of the Australian marsupials. Of fifty living species, thirty are confined to Madagascar, and the lemurs are there exceedingly