probably representing clefts.

LEGENTIL.--A large walled-plain, close to the limb, S. of Bailly.

FOURTH QUADRANT

WEST LONGITUDE 90 deg. TO 60 deg.

KASTNER.--A large walled-plain at the S. end of the Mare Smythii, too
near the limb for satisfactory observation.

MACLAURIN.--The principal member of a group of irregular ring-plains on
the W. side of the Mare Foecunditatis, a little S. of the lunar equator.
Schmidt shows no details within it, except a small crater on the E. side
of the floor.

WEBB.--A ring-plain E. of Maclaurin, about 14 miles in diameter, with a
dusky floor, enclosed by a bright rim, on the N.E. side of which there is
a small crater. Schmidt seems to have overlooked the central hill.

LANGRENUS.--This noble circumvallation, the most northerly of the
meridional chain of immense walled-plains, extending for more than 600
miles from near the equator to S. lat. 40 deg., would, but for its
propinquity to the limb, rank with Copernicus (which in many respects it
resembles) among the most striking objects on the surface of the moon.
Its length is about 90 miles from N. to S., and its breadth fully as
much. In shape it approximates very closely to that of a foreshortened
regular hexagon. The walls, which at one point on the E. rise to an
altitude of nearly 10,000 feet, are continuous, except on this side,
where they are broken by the interference of an irregular depression, and
on the extreme S., where they are intersected by cross-valleys. Within,
the terraces are remarkably distinct, and the intervening valleys
strongly marked. The brilliant compound central mountain rises at its
loftiest peak to a height of more than 3000 feet. On the N. of it is an
obscure circular ring, which may possibly merely represent a fortuitous
combination of ridges, though it has all the appearance of a modified
ring-plain. On the Mare, some distance N.E. of the formation, is a group
of three ring-plains, with two small craters (associated with a ridge) on
the N. of them. Two of the more westerly of these objects have prominent
central mountains, and the third a very dark interior. At least three
bright streaks originate on the E. flank of Langrenus, which, diverging
widely, traverse the Mare Foecunditatis.

[FLATTENINGS ON THE MOON'S WESTERN LIMB.--About thirty years ago, the
Rev. Henry Cooper Key drew attention to certain flattenings which he had
noted on the W. limb, which are very apparent under favourable condi