Two gigantic craters, Eudoxus being nearly 35 miles in diameter and upwards of 11,000 feet deep, while Aristotle is about 48 miles in diameter, and about 10,000 feet deep (measuring from the summit of the rampart to the plateau). These two magnificent craters present all the true volcanic characteristics in a remarkable degree. The outsides as well as the insides of their vast surrounding walls or banks display on the grandest scale the landslip feature, the result of the over-piling of the ejected material, and the consequent crushing down and crumbling of the substructure. The true eruptive character of the action which formed the craters is well evinced by the existence of the groups of conical mountains which occupy the centres of their circular plateaux, since these conical mountains, there can be little doubt, stand over what were once the vents from whence the ejected matter of the craters was discharged. On the west side of these grand craters may be seen myriads of comparatively minute ones (we use the expression “comparatively minute,” although most of them are fully a mile in diameter). So thickly are these small craters crowded together, that counting them is totally out of the question; in our original notes we have termed them “Froth craters” as the most characteristic description of their aspect. The exterior banks of Aristotle are characterized by radial ridges or spurs: these are most probably the result of the flowing down of great currents of very fluid lava. To the east of the craters some very lofty mountains of exudation may be seen, and immediately beyond them an extensive district of smaller mountains of the same class, so thickly crowded together as under favourable illumination to present a multitude of brilliant points of light contrasted by intervening deep shade. On the west bank of Aristotle a very perfect crater may be seen, 27 miles in diameter, having all the usual characteristic features. About 40 miles to the east of Eudoxus there is a fine example of a crack or fissure extending fully 50 miles—30 miles through a plain, and the remaining 20 miles cutting through a group of very lofty mountains. This great crack is worthy of attention, as giving evidence of the deep-seated nature of the force which occasioned it, inasmuch as it disregards all surface impediments, traversing plain and group of mountains alike. There are several other features in and around these two magnificent craters well worthy of careful observation and scrutiny, all of them excellent types of their respective classes. TRIESNEKER, 150 (35·5—109·8). Plate XI. A fine example of a normal lunar volcanic crater, having all the usual characteristic features in great perfection. Its diameter is about 20 miles, and it possesses a good example of the central cone and also of interior terracing.