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ring-plain W. of Playfair.

ABENEZRA.--When observed near the morning terminator, this noteworthy
ring-plain, 27 miles in diameter, seems to be divided into two by a
curved ridge which traverses the formation from N. to S., and extends
beyond its limits. The irregular border rises on the W. to a height of
more than 14,000 feet above the deeply-sunken floor, which includes
several craters, hills, and ridges.

APIANUS.--A magnificent ring-plain, 38 miles in diameter, N.W. of
Aliacensis, with lofty terraced walls, rising on the N.E. to about 9000
feet above the interior, and crowned on the W. by three large conspicuous
craters. The border is broken on the N. by a smaller depression and a
large ring with low walls. The dark-grey floor appears to be devoid of
conspicuous detail.

PLAYFAIR.--A ring-plain, 28 miles in diameter, with massive walls. It is
situated on the N. of Apianus, and is connected with it by a mountain
arm. The rampart is tolerably continuous, but varies considerably in
altitude, rising on the S. to a height of more than 8000 feet above the
interior. On the E., extending towards Blanchinus, is a magnificent
unnamed formation, bounded on the E. by a broad lofty rampart flanking
Blanchinus, Lacaille, Delaunay, and Faye; and on the W. by Playfair and
the mountain arm just mentioned. It is fully 60 miles in length from N.
to S. Sunrise on this region affords a fine spectacle to the observer
with a large telescope. The best phase is when the morning terminator
intersects Aliacensis, as at this time the long jagged shadows of the E.
wall of Playfair and of the mountain arm are very prominent on the
smooth, greyish-blue surface of this immense enclosure.

PONTANUS.--An irregular ring-plain, 28 miles in diameter, S.S.W. of
Azophi, with a low broken border, interrupted on the S.W. by a smaller
ring-plain, which forms one of a group extending towards the S.W. The
dark floor includes a central mountain.

ALIACENSIS.--This ring-plain, 53 miles in diameter, with its neighbour
Werner on the N.E., are beautiful telescopic objects under a low sun. Its
lofty terraced border rises at one peak on the E. to the tremendous
height of 16,500 feet, and at another on the opposite side to nearly
12,000 feet above the floor. The wall on the S. is broken by a crater,
and on the W. traversed by narrow passes. There is also a prominent
crater on the inner slope of the N.E. wall. The floor includes a small
mountain, several littl