ARISTOTELES.—­A magnificent ring-plain, 60 miles in diameter, with a complex border, surmounted by peaks, rising to nearly 11,000 feet above the floor, one of which on the W., pertaining to a terrace, stands out as a brilliant spot in the midst of shadow when the interior is filled with shadow.  The formation presents its most striking aspect at sunrise, when the shadow of the W. wall just covers the floor, and the brilliant inner slope of the E. wall with the little crater on its crest is fully illuminated.  At this phase the details of the terraces are seen to the best advantage.  The arrangement of the parallel ridges and rows of hills on the N.E. and S.W. is likewise better seen at this time than under an evening sun.  A bright and deep ring-plain, about 10 miles in diameter, with a distinct central mountain, is connected with the W. wall.

EGEDE.—­A lozenge-shaped formation, about 18 miles from corner to corner, bounded by walls scarcely more than 400 feet in height.  It is consequently only traceable under very oblique illumination.

THE GREAT ALPINE VALLEY.—­A great wedge-shaped depression, cutting through the Alps W. of Plato, from W.N.W. to E.S.E.  It is more than 80 miles in length, and varies in breadth from 6 miles on the S. to less than 4 miles on the N., where it approaches the S. border of the Mare Frigoris.  For a greater part of its extent it is bounded on the S.W. side by a precipitous linear cliff, which, under a low evening sun, is seen to be fringed by a row of bright little hills.  These are traceable up to one of the great mountain masses of the Alps, forming the S.W. side of the great oval-shaped expansion of the valley, whose shape has been appropriately compared to that of a Florence oil-flask, and which Webb terms “a grand amphitheatre.”  On the opposite or N.E. side, the boundary of the valley is less regular, following a more or less undulating line up to a point opposite, and a little N. of, the great mountain mass, where it abuts on a shallow quasi enclosure with lofty walls, which, projecting westwards, considerably diminish the width of the valley.  South of this lies another curved mountain ring, which still farther narrows it.  This curtailment in width represents the neck of the flask, and is apparently about 16 or 17 miles in length, and from 3 to 4 miles in breadth, forming a gorge, bordered on the W. by nearly vertical cliffs, towering thousands of feet above the bottom of the valley; and on the E. by many peaked mountains of still greater altitude.  At the entrance to the “amphitheatre,” the actual distance between the colossal rocks which flank the defile is certainly not much more than 2 miles.  From this standpoint the view across the level interior of the elliptical plain would be of extraordinary magnificence.  Towards the S., but more than 12 miles distant, the outlook of an observer would be limited by some of the loftiest peaks of the Alps, whose flanks form the boundary of the enclosure, through