ALFRAGANUS.—­A large bright crater, about 9 miles in diameter, with very steep walls, some distance S.S.W. of Delambre, and standing on the W. edge of a large but very shallow and irregular depression W. of Taylor.  There is a remarkable chain of craters on the W. of it.  Alfraganus is the centre of a system of light streaks radiating in all directions, one ray extending through Cyrillus to Fracastorius.

TAYLOR.—­A deep spindle-shaped ring-plain, S. of Delambre, about 22 miles in length.  The wall appears to be everywhere continuous, except at the extreme N. and S. ends, where there are small craters.  The outer slopes, both on the E. and W., are very broad and prominent, but apparently not terraced.  There is an inconspicuous central hill.  On the W. is the irregular enclosure, already referred to under Alfraganus.  Three or four short winding valleys traverse the N. edge of this formation, and descend to the dark floor.  On the N.E. is the remarkable ring-plain Taylor a, 18 miles in diameter, rising, at an almost isolated mountain mass on the E. border, to a height of 7000 feet above the interior.  The more regular and W. section of this formation is not so lofty, and falls with a gentle slope to the dark uneven floor, on which there is some detail in the shape of small bright ridges and mounds.  On the surface, N.W. of Taylor a, is a curious linear row of bright little hills.  Taylor and the vicinity is better seen under low evening illumination than under morning light.

HIPPARCHUS.—­Except under a low sun, this immense walled-plain is by no means so striking an object as a glance at its representation on a chart of the moon would lead one to expect; for the border, in nearly every part of it, bears unmistakable evidence of wreck and ruin, its continuity being interrupted by depressions, transverse valleys, and gaps, and it nowhere attains a great altitude.  This imperfect enclosure extends 97 miles from N. to S., and about 88 miles from E. to W., and in shape approximates to that of a rhombus with curved sides.  One of the most prominent bright craters on its border is Hipparchus G, on the W. Another, of about the same size, is Hipparchus E, on the N. of Horrocks.  On the E. there is a moderately bright crater, Hipparchus F; and S. of this, on the same side, two others, K and I. The interior is crossed by many ridges, and near the centre includes the relics of a low ring, traversed by a narrow rill-like valley.  Schmidt shows a cleft running from F across the floor to the S. border.

[A valuable monograph of Hipparchus, by Mr. W.B.  Birt, was published in 1870.]

HORROCKS.—­This fine ring-plain, 18 miles in diameter, stands on the N. side of the interior of Hipparchus, close to the border.  It has a continuous wall, rising on the E. to a height of nearly 8000 feet above the interior, and a distinct central mountain.