Madagascar

In deposits of the Jurassic the bones of some enormous terres trial lizards have been brought to light, belonging to Sauropodous dinosaurs of the genera Bothriospondylus and Titanosaurus, and to a Theropod of the genus Megalosaurus. In the beds of the Lower Oolite portions of the skull of a reptile resembling the gavial of the Ganges had been previously discovered, from which a new genus called Steneosaurus has been founded. Since the French occupation (1895) considerable additions have been made to our knowledge of the fossil fauna of Madagascar, from researches made both on the west and south-west coasts (at Belo and Ambo lisatrana), and in the interior (at Antsirabe), especially in the rich deposits near Tsarazaza (Ampasambazimba), to the north west of Lake Itasy. From these various localities the sub-fossil remains of 13 or 14 extinct species of lemuroid animals have been obtained, and have been classified under five new genera : viz., Megaladapis (3 sp.), Palaeoprokithecus (3 sp.), Archaeolemur (2 sp.), Bradylemur (I sp.) and Hadropithecus (I sp.), together with three new species of lemur. Of these, the Archaeolemurs seem to have combined the characteristics of lemuroid animals with those of the monkeys, while Hadropithecus is pronounced to be the nearest known link with them. About 28o species of Madagascar invertebrate fossils are known, including Molluscs, Foraminifera, Echinoderms, etc.

Physical Features.

Madagascar has few indentations, con sidering its great extent of shore-line. The east coast is almost a straight line, with dunes, lagoons and alluvial plains; Tamatave, the chief port on this side of the island, being only protected by coral reefs. The only indentations are the Bays of of Port Louquez, and, at almost the extreme northern point of the island, Diego-Suarez bay, one of the finest harbours in the world. The north-western side of Madagascar, on which the mountains often reach the sea, is broken up by a number of inlets, some of them land-locked and of considerable size. South of Cape St. Andrew, the north-west angle of the island, the low, flat coast line is unbroken until the estuary of the river Onilahy, or St. Augustine bay, is reached. The south coast, though higher, has neither bays nor capes.

The largest coastal islands are Ste. Marie, near the eastern coast, a narrow island about 35 m. long, and Nossi-be (q.v.), op posite Ampasindava bay on the north-west coast. Except the Minnow group, north of Nossi-be, the rest are merely rocky islets, chiefly of coral.

On the east the plains vary from io to so m. in breadth, but on the west they exceed, in some localities, loo miles. From these coast-plains the ground rises by successive ranges of hills to the high interior plateau. This elevated region, the edge of which is formed on all sides by cliffs several hundreds of metres in height, is broken in all directions by mountains, from which the crys talline rocks show most frequently as huge bosses, and in certain regions present very varied and picturesque outlines. The high

est mountain mass, east-centrally situated, is the ancient extinct volcano, Ankaratra, three of the highest points varying in eleva tion from 7,284 to 8,635 ft. above the sea, and from 4,000 to 5,000 ft. above the general level of the surrounding country. The lof t iest of these is named Tsi-afa-javona, i.e., "That which the mists cannot climb." The highest point in the island is Amboro, about 9,490 ft., in the northern province of Antankara. The other massifs are, on the north the Tsaratanana, on the south-east that of Iratsy and Horembe, rugged and bare, on the south the Vohi mainty, dominated by the volcano Antandroy, etc. One of the finest of the Madagascar mountains is an isolated volcanic mass near the northern point of the island called Ambohitra. The east slope of Madagascar is the edge of a fault, and slopes steeply to the Indian ocean, heights of more than 1,5oo metres fringing depths of 4,000 to 5,00o metres. The western side, on the other hand, slopes gradually towards the Mozambique channel, the depth of which is more than 3,000 metres. The plateau is dissected by transverse valleys, which have served as migration routes. Be tween the mountain heights stretch fertile plains of lake alluvium, such as the Imerina and the Plain of Basileo, the rice-fields of which have given rise to towns like Antananarivo. Longitudinal valleys like those of the Ankay and of Lake Alhotra are equally fertile.

There are no arid districts, except in the extreme south-west and towards the southern point of the island. The general sur face of the interior highland consists of bare rolling moor-like country, with a great amount of red, clay-like soil, while the valleys have a rich humus of bluish-black alluvium.

The chief rivers flow to the west and north-west sides of the island. The eastern streams are all less in size, except the Man ger°, in valley of Ankay, which flows parallel with the coast. They become navigable at best only when they have left the pla teau, from which they often fall in cataracts, as in the case of the Ikopa ; and all are more or less closed at their outlets by sand bars. The well-watered eastern slope is rich in short torrents, with many waterfalls. The most important are the Manger° and the Mananara, formed by three large rivers from the plateau. On the more gradual western slope the rivers, although broken by rapids at their descent from the plateau, are longer and more important, but they often end in deltas. The largest river is the Betsiboka, which receives on its left the Ikopa, on which stands Antananarivo. The Betsiboka is navigable for 7o km., and in the rainy season steamers go up the Ikopa as far as Mevatanana. To the north, the Sofia has a fertile well-populated valley, to the south the Tsiribihina, the Onitahy and the Mangoky are considerable streams.