e two others much larger,
that nearer to Fourier being traversed by one cleft, and the other by two
clefts, crossing near the centre of the floor.

CLAUSIUS.--A small bright ring-plain in an isolated position N.W. of
Schickard, with a crater both on its N. and S. rim, and a faint central
hill.

LACROIX.--A ring-plain 20 miles in diameter, N. of Schickard. It has a
prominent central mountain.

SCHICKARD.--One of the largest wall-surrounded plains on the visible
surface of the moon, extending about 134 miles from N. to S., and about
the same from E. to W., enclosing a nearly level area, abounding in
detail. Its border, to a great extent linear, is very irregular, and much
broken by the interposition of small ring-plains and craters, and on the
N. by cross-valleys. Its general height is about 4000 feet, the loftiest
peak on the W. wall rising to more than 9000 feet above the floor. The
inner slopes of this vast rampart are very complex, especially on the E.,
where many terraces and depressions may be seen under suitable
illumination. There are three large ring-plains in the interior, all of
them S. of the centre; and at least five smaller ones near the inner foot
of the E. wall, which can only be well observed when libration is
favourable. The two more easterly of the large ring-plains are connected
by a cleft, and there are several short clefts and crater-rows associated
with the smaller ring-plains. On the N. side of the area is a number of
minute craters. The floor is diversified by two large dark markings--an
oblong patch on the S.W. side, abutting on the wall, being the more
remarkable; and a dusky area, occupying a great portion of the N. part of
the floor, and extending up to the N. border. This is traversed by a
light streak running from N. to S., which is the site of a row of minute
craters.

LEHMANN.--A ring-plain, about 28 miles in length, on the N. of Schickard,
with which it is connected by a number of cross-valleys.

DREBBEL.--A bright ring-plain, 18 miles in diameter, on the N.W. of
Schickard, with a lofty irregular border (especially on the W.),
exhibiting a well-marked terrace on the E., a distinct gap on the N., and
a small crater on the S.E. rim. On a dusky area between it and Schickard
stand three prominent deep craters.

PHOCYLIDES.--This extraordinary walled plain, with its neighbouring
enclosures, is structurally very remarkable and suggestive. It consists
of a large irregular formation, with