disposed parallel with the main range and the seaboard. Old terraced beaches encircling the upland Sihanaka and Ankai valleys clearly show that the lacustrine waters at one time stood fully 1,100 feet above their present level. South of Tamatave and Andovoranto the most copious stream on the east slope of the island is the Onibé River, which also receives Fig. 132. — Lagoons on the east coast of Madagascar.
some contributions from the longitudinal valleys, but which is chiefly fed by the torrents descending from the great central mass of the Ankaratra highlands. Farther south, in the Betsileo territory, rises the Matitanana, or "Dead hand," a sacred stream smaller than the Onibé, and with a more obstructed course. One of its cataracts at the issue of the mountains is no less than 600 feet high, and near it rises an abundant thermal spring.
Although the rivers flowing eastwards to the Indian Ocean are closed to navigation above their estuaries, these estuaries themselves, ramifying inland and connected together by lateral channels, present a great extent of navigable waters along the coastlands. A few cuttings made here and there across the sands and coral banks would enable small steamers to ply in smooth water all the way from Ivondru, near Tamatave, to the mouth of the Matitanana — that is to say. for a distance of over 300 miles, reckoning all the windings of the channel. Already, in 1864, Captain Rooke had thoroughly surveyed this water highway, which is here and there obstructed by mud banks and the stakes of the fishermen set all in a row. The ampanalana, or portages, occurring at various points of the future canal, which King Radama I. had already began to construct, have at high water a collective length of about 28 miles. ;
