ALMANON.—­This ring-plain, with its companion Abulfeda on the N.E., is a very interesting telescopic object.  It is about 36 miles in diameter, and is surrounded by an irregular border of polygonal shape, the greatest altitude of which is about 6000 feet above the floor on the W. It is slightly terraced, and is broken on the S. by a deep crater pertaining to the bright and large formation Tacitus b, the E. border of which casts a fine double-peaked shadow at sunrise.  On the N.W. there is another bright crater, the largest of the row, running in a W.S.W. direction, and forming a W. extension of the remarkable crater-chain tangential to the borders of Almanon and Abulfeda.  The only objects on the floor are three little hills, in a line, near the centre, a winding ridge on the W. side of it, and two or three other low elevations.

ABULFEDA.—­A larger and more massive formation than Almanon, 39 miles in diameter, the E. wall rising about 10,000 feet above the interior, which is depressed more than 3000 feet.  It is continuous on the W., but much broken by transverse valleys on the S.E., and by little depressions on the N. On the S.E. originates the very curious bright crater-row which runs in a straight line to the N.W. wall of Almanon, crossing for the first few miles the lofty table-land lying on the S.E. side of the border.  With the exception of a low central mountain, the interior of Abulfeda contains no visible detail.  The rampart is finely terraced on the E. and W. The E. glacis is very rugged.

ARGELANDER.—­This conspicuous ring-plain, about 20 miles in diameter, is, if we except two smaller inosculating rings on the S.W. flank of Albategnius, the most northerly of a remarkable serpentine chain of seven moderately-sized formations, extending for nearly 180 miles from the S.W. of Parrot to the N. side of Blanchinus.  Its border is lofty, slightly terraced within, and includes a central peak.

AIRY.—­About 22 miles in diameter, connected with Argelander by a depression bounded by linear walls.  Its border, double on the S.E., is broken on the S. by a prominent crater, with a smaller companion on the W. of it; and again on the N.E. by another not so conspicuous.  It has a central peak.  The next link in the chain of ring-plains is Airy c, a very irregular object, somewhat larger, and with, for the most part, linear walls.

DONATI.—­A ring-plain on the S. of Airy c, about 22 miles in greatest length.  It is very irregular in outline, with a lofty broken border, especially on the N. and S., where there are wide gaps.  There is another ring on the S.E.

FAYE.—­The direction of the chain swerves considerably towards the E. at this formation, which resembles Donati both in size and in irregularity of outline.  The wall, where it is not broken, is slightly terraced.  There is a craterlet on the S. rim and a central crater in the interior.

DELAUNAY.—­Adjoins Faye on the S.E., and is a larger and more complex object, of irregular form, with very lofty peaks on its border.  A prominent ridge of great height traverses the formation from N. to S., abutting on the W. border of Lacaille.  Delaunay is the last link in the chain commencing with Argelander.