almost tunnel-like, among the rank vegetation; and where a stranger might easily be lost in the watery and reedy wastes around him. There can be no doubt that the present lake is but a small remnant of a much larger one; for, at a not very distant period, the water must have covered the whole plain of Antsihànaka, thus forming a lake five or six times the size of the present Alaotra. But at a yet earlier period still, this lake extended for a hundred miles farther south, down the Ankay plain, and for at least two hundred miles farther north, forming an immense extent of water, not much unlike the Tànganyika in Central Africa in size and outline, and of considerable depth; for Mr Baron found numerous indications of old shore-lines at elevations of eleven to twelve hundred feet above the present level. Doubtless, the gradual lowering of the valleys of the Mangòro to the south, and of the Màningòry to the north-east, drained off this great lake, leaving only the present comparatively small sheet of water as its representative. [Sidenote: BIRD LIFE] To an ordinary observer the Alaotra lake presents a good deal of bird life, as well as the large reptiles which bask in the sun on its shores. But to those who will examine more closely and will use a good microscope, there are minute forms of life, both animal and vegetable, which are wonderful for their beauty and their variety. Among the latter are the Algæ, of which my late friend, Mr Baron, made a collection, mostly from the neighbourhood of Alaotra, including a hundred and eighty species, of which seventy proved to be new to science. In a quarto pamphlet of fifty pages, with plates of two hundred different figures, these fresh-water algæ were minutely described, as belonging to thirteen different orders and thirty-one genera.[19] Many new and interesting species were thus revealed, and considerable additional knowledge of the distribution of known forms attained. Without actual inspection of the plates it is difficult to give any clear notion of the various remarkable, often strange, and frequently beautiful forms of these lowly organised plants as revealed by the microscope. The bi-lobed outlines of the _Cosmaria_ are especially noticeable, and hardly less so are the stellate, triangular and multangular forms of other species. It is difficult to believe that some of these remarkable organisms are plants at all; in many cases they are more like some beautiful shell, delicately and elaborately sculptured; while in others they take the form of a simple cell—round, oval or triangular—often as if about to increase by fissure; while others again have curious processes, more like those of some grotesque polyp than anything belonging to the vegetable kingdom. These plants are additional illustrations of the wonders that lie hidden from ordinary observation in the mud of almost every pond and in the slime that gathers round almost every water-plant.