de surpasses many terrestrial mountain
systems--as, for example, the Snowdonian group. The massive barrier
between Alpetragius and Alphonsus deserves careful scrutiny, and should
be examined under a moderately low morning sun. On the E., towards
Lassell, stands a brilliant light-surrounded crater.

ARZACHEL.--Another magnificent object, associated on the N. with
Alphonsus, about 66 miles in diameter, and encircled by a massive complex
rampart, rising at one point more than 13,000 feet above a depressed
floor. It presents some very suggestive examples of terraces and large
depressions, the latter especially well seen on the S.E. The bright
interior includes a large central mountain with a digitated base on the
S.E., some smaller hills on the S. of it, a deep crater W. of it (with
small craters N. and S.), and, between the crater and the foot of the W.
wall, a very curious winding cleft.

LASSELL.--This ring-plain, some 14 miles in diameter, is irregular both
as regards its outline and the width of its rampart. There is a crater on
the crest of the N.W. wall, just above a notable break in its continuity
through which a ridge from the N.W. passes. There is another crater on
the opposite side. The central mountain is small and difficult to see.
About 20 miles N.E. of Lassell is a remarkable mountain group associated
with a bright crater, and further on in the same direction is a light
oval area, about 10 miles across, with a crater (Alpetragius _d_) on its
S. edge. Madler described this area as a bright crater, 5 miles in
diameter, which now it certainly is not.

LALANDE.--A very deep ring-plain, about 14 miles in diameter, N.E. of
Ptolemaeus, with bright terraced walls, some 6000 feet above the floor,
which contains a low central mountain. On the N. is the long cleft
running, with some interruptions, in a W.N.W. direction towards Reaumur.

DAVY.--A deep irregular ring-plain, 23 miles across, on the Mare E. of
Alphonsus. There is a deep crater with a bright rim on its S.W. wall, and
E. of this a notable gap. There is also a wide opening on the N. The E.
wall is of the linear type. A cleft crosses the interior.

GUERIKE.--The most southerly member of a remarkable group of partially
destroyed walled-plains, standing in an isolated position in the Mare
Nubium. Its border, on the W. and N. especially, is much broken, and
never rises much more than 2000 feet above the Mare, except at one place
on the N., where there is a mou