even under a low morning sun. On
the opposite side it is boldly terraced, and has a large crater on its
summit. The interior, the tone of which is conspicuously darker than that
of the region outside, contains a small central hill, with two craters
connected with it. The low N.W. margin is traversed by a delicate valley,
which, originating on the N. side of the great plain, crosses the W.
quarter of Lexell and terminates apparently on the S.W. side of the
floor.

HELL.--A prominent ring-plain, about 18 miles in diameter, on the E. side
of the great plain. There is a central mountain and many ridges within.

BALL.--A somewhat smaller ring-plain on the S.E. edge of the great plain,
with a lofty terraced border and a central mountain more than 2000 feet
high. There are two large irregular depressions on the W. of the
formation, a crater on the S., and a smaller one on the N. wall.

PITATUS.--This remarkable object, 58 miles in diameter, with Hesiodus,
its companion on the E., situated at the extreme S. end of the Mare
Nubium, afford good examples of a class of formations which exhibit
undoubted signs of partial destruction, from some unknown cause, on that
side of them which faces the Mare. On every side but the N., Pitatus is a
walled plain of an especially massive type, the border on the S.E.
furnishing one of the finest examples of terraces to be found on the
visible surface. On the S.W., two parallel rows of large crateriform
depressions, perhaps the most remarkable of their kind, extend for 60
miles or more to the W. flank of Gauricus. On the N.W., the rampart
includes many curious irregular depressions and craters, and gradually
diminishes in height, till, for a space of about 12 miles on the N.,
there can hardly be said to be any border at all, its site being marked
by some inconsiderable mounds and shallow hollows. There is a small
bright central mountain on the floor, and, S. of it, two larger but lower
elevations. A distinct straight cleft traverses the N.W. side of the
interior very near the wall, to which it forms an apparent chord, and a
second cleft occupies a similar position with respect to the bright N.E.
border. A narrow pass forms a communication with the interior of
Hesiodus.

HESIODUS.--This walled-plain, little more than half the diameter of the
last, has an irregular outline, and for the most part linear walls, which
on the S. are massive and lofty (4000 feet), but on the N. very low, and
broken