In one of the valleys to the west of the Ankàratra _massif_ there is a river called Antsèsika, which is quite lost to sight and sound for about a mile and a quarter. It disappears under a mass of enormous gneiss boulders, which have filled up the valley of the river, so that the stream runs for a considerable distance at an immense depth below the general level. In the upper part of its course, this river passes over a series of grand falls before diving deep into the earth, as just described. Its name of Antsèsika is very appropriate, as it means “that which is thrust in.” [Sidenote: EXTINCT LEMUROID ANIMALS] Some members of the extinct fauna of Madagascar (Æpyornis, hippopotamus and crocodile) have been already noticed, but we must here mention other discoveries made within the last few years. About twenty years ago a skull, in a sub-fossil condition, was discovered on the south-west of the island, and proved to be that of a gigantic form of lemuroid animal. This skull is very much larger and longer than those of any existing lemurs (which are fairly globular in shape), and belonged to a creature more like a gorilla in size and strength. More recently, at a place called Ampàsambazìmba, which is five miles north of Itàsy, the remains of a number of species (fourteen or fifteen) of extinct lemuroid animals have been discovered; in fact this spot seems like the burial-ground of a whole fauna now entirely passed away, and probably quite recently; for Dr Standing, who conducted the excavations, thinks that not more than five centuries have elapsed since some at least of these animals were living. Several new species of apparently quite distinct genera have been disinterred; they are mostly larger than any existing lemuroid; and some of them form links between the true monkeys and the lemurs—families of primates now very distinct from each other. Some of these newly discovered creatures seem, from the position of the nostrils, eyes and ears (like those of the hippopotamus), to have been adapted to a partially aquatic life. There is abundant evidence of the former existence of extensive lakes in the surrounding country, where now there is only marsh or dry land. Others of these extinct animals were arboreal; and from the remains of leaves and branches, together with bones, not to mention other evidence, there is no doubt that much of what is now open down and bare hill was formerly covered with forest. There was therefore appropriate habitat for them all; and their needs, whether in water or on the trees, would be met by the former conditions of the country. It seems highly probable that the physical changes of the interior have been the chief cause of the extinction of so many living creatures, although the advent of man upon the scene may have hastened the process.[23] [Sidenote: PHYSICAL CHANGES]