the region called Elysium, one of the brightest parts of the planet. It was here that Mr. Douglass made his interesting observation, last September, of a remarkable change of tint from bright to sombre, and back to bright again, in the course of forty-eight hours; suggesting perhaps the formation and dissipation of cloud, perhaps the deposition and subsequent melting of hoar-frost over an area of some hundreds of square miles.

Returning to the Mare Cimmerium, we observe in the middle of it a long, lighter streak, Cimmeria, scarcely perceptible at this last opposition, and, barring its western end, the second in the procession of similarly inclined peninsulas that follow one another westward upon this side of the planet, the peninsula Hesperia, a place with a history, as will appear later on.

In the next picture (Plate XI.) Hesperia is central, dividing the Mare Cimmerium on the left from the Mare Tyrrhenum on the right. The lower end of the latter is called the Syrtis Minor, in contradistinction to the Syrtis Major, which is just appearing round the western limb. From the bay, so to speak, upon the left of Hesperia, two canals proceed down the disk in divergent directions,--the most easterly one the Aethiops, the other the Achelous. From the Syrtis Minor proceed two others, more or less similarly inclined,--the Lethes and the Amenthes.

To the west of Hesperia and parallel to it is a third comet-tail peninsula, Lemuria, connecting Ausonia at the south with Libya to the north, Libya being upon the equator.

This region (Plate XII.) is interesting as having been the scene of great changes at previous oppositions. There used to be a spot, the Lake Moeris, in the midst of it, joined by the Nepenthes--the canal running east and west about eight degrees north of the equator--to the Syrtis Major, the great dark gulf somewhat to the west of the central meridian in the picture. Latterly the Syrtis Major seems to have encroached upon Libya, and, at the last opposition, only the faintest glimpses could be got of Lake Moeris, which showed chiefly as a bay of the Syrtis Major itself. Here, as elsewhere, I use aquatic names with terrestrial understanding.

Parallel in a general way to the Nepenthes, and about as much below it as it is below the coast-line, lies the Astapus, which joins the bottom of the Syrtis Major to the ends of the Amenthes, Lethes, and Achelous.

In Plate XIII. two features are striking, both not far from central on the disk,--the lower, the Syrtis Major; the upper, Hellas. The Syrtis Major was the first marking to be certainly recognized on Mars. It appears in a drawing by Huyghens made on October 13, 1659, the first drawing of Mars worthy the name ever made by man, and reproduced on page 20 from Flammarion's "La Planete Mars." It is thus our oldest Martian acquaintance; Hellas is the surprisingly round, bright area nearly on the meridian, and nearly half way from the equator to the south pole. It is very strangely quartered by two canals, the Alpheus; dividing it almost due north and south; and the Peneus, cutting it almost due east and west. Between it and the Syrtis Major is the Mare Hadriaticum, a blue-green area intersected by bright causeways and seamed by dark canals.

In the lower right-hand portion of the disk is an important region, bounded on the east by the Syrtis Major, on the north by the Nilosyrtis and the Protonilus, on the west by the Hiddekel, and on the south by the long dark area to the north of Deucalionis Regio; its southeastern cape is the Hammonis Cornu; its southwestern one, which appears in Plate XIV., is the Edom promontory. It is a region prolific in double canals. The two most important of these are the Phison and the Euphrates. Both start from the centre of the coast of the long dark area between the Deucalionis Regio and the continent, and run, the Phison northeast to the western end of the Nilosyrtis, in longitude 300 degrees, latitude 33 degrees north; the Euphrates, nearly due north to the Lacus Ismenius, longitude 337 degrees, latitude 37 degrees north, where it connects with the Hiddekel. Parallel to the coast-line and about 15 degrees to the north of it is, on the east, the Typhon, shown double; on the west the Orontes, still single. Two other doubles shown in the picture I saw also in this region, though I am not yet certain that they are distinct from the Phison