HALLEY.—­A ring-plain, 21 miles in diameter, on the S.W. border of Hipparchus, with a bright wall, rising at one point on the E. to a height of 7500 feet above the floor, which is depressed about 4000 feet below the surface.  Two craterlets on the floor, one discovered by Birt on Rutherfurd’s photogram of 1865, and the other by Gaudibert, raised a suspicion of recent lunar activity within this ring.  A magnificent valley, shown in part by Schmidt as a crater-row, runs from the S. of Halley to the W. side of Albategnius.

HIND.—­A ring-plain, 16 miles in diameter, a few miles W. of Halley, with a peak on its E. wall 10,000 feet above the floor.  The border is broken both on the S.E. and N.E. by small craters.

[Horrocks, Halley, and Hind may be regarded as strictly belonging to Hipparchus.]

ALBATEGNIUS.—­A magnificent walled-plain, 65 miles in diameter, adjoining Hipparchus on the S., surrounded by a massive complex rampart, prominently terraced, including many depressions, and crossed by several valleys.  It is surmounted by very lofty peaks, one of which on the N.E. stands nearly 15,000 feet above the floor.  The great ring-plain Albategnius A, 28 miles in diameter, intrudes far within the limits of the formation on the E., and its towering crest rises more than 10,000 feet above its floor, on which there is a small central mountain.  The central mountain of Albategnius is more than 4000 feet high, and, with the exception of a few minor elevations, is the only prominent feature in the interior, though there are many small craters.  Schmidt counted forty with the Berlin refractor, among them 12 on the E. side, arranged like a string of pearls.

PARROT.—­An irregularly-shaped formation, 41 miles in diameter, S. of Albategnius, with a very discontinuous margin, interrupted on every side by gaps and depressions, large and small; the most considerable of which is the regular ring-plain Parrot a, on the E. An especially fine valley, shown by Schmidt to consist in part of large inosculating craters, cuts through the wall on the S.W., and runs on the E. side of Argelander towards Airy.  The floor of Parrot is very rugged.

DESCARTES.—­This object, about 30 miles in diameter, situated N.W. of Abulfeda, is bounded by ill-defined, broken, and comparatively low walls; interrupted on the S.E. by a fine crater, Descartes A, and on the S.W. by another, smaller.  There is also a brilliant crater outside on the N.W.  Schmidt shows a crater-row on the floor, which I have seen as a cleft.

DOLLOND.—­A bright crater, about 6 miles in diameter, on the N.E. side of Descartes.  Between it and the latter there is a rill-valley.

TACITUS.—­A bright ring-plain, about 28 miles in diameter, a few miles E. of Catherina, with a lofty wall rising both on the E. and W. to more than 11,000 feet above the floor.  Its continuity is broken on the N. by a gap occupied by a depression, and there is a conspicuous crater below the crest on the S.W.  The central mountain is connected with the N. wall by a ridge, recalling the same arrangement within Madler.  A range of lofty hills, an offshoot of the Altai range, extends from Tacitus towards Fermat.