SANTBECH.--A very prominent ring-plain, 46 miles in diameter, on the S.E. side of the Mare Foecunditatis, W. of Fracastorius. The continuity of its fine lofty rampart is broken on the W., where it rises nearly 10,000 feet above the floor, by a brilliant little crater just below the crest, and by a narrow gap on the S. The wall on the E. towers to a height of 15,000 feet above the interior. On its broad outer slope, near the summit, there is a fine crater, and S. of this running obliquely down the slope a distinct valley. On the N.E., where the _glacis_ runs down to the level of the surrounding plain, there is a large crateriform object with a broken N. border, and a small crater opposite the opening. A long coarse valley runs from this latter object in a N.E. direction to the region W. of Bohnenberger. Santbech contains a prominent central peak. BIOT.--A brilliant little ring-plain, scarcely more than 7 miles in diameter, standing in an isolated position in the Mare Foecunditatis N.E. of Wrottesley. There is a number of bright streaks in its neighbourhood; and a few miles E. of it, in the hilly region W. of Santbech, another conspicuous crater of about the same size. BORDA.--A ring-plain about 25 miles in diameter, S.S.W. of Santbech, with a rampart low on the N. and S., but elsewhere of considerable height, and a very conspicuous central mountain. A wide deep valley flanked by lofty mountains extends from the N. wall for many miles towards the N.W. It is an especially noteworthy object when the W. wall of Santbech is on the evening terminator, as its somewhat winding course, indicated by the bright summit-ridges of the bordering mountains, can be followed some hours before either the interior of the valley or the region between it and Santbech are in sunlight. Among the mountains W. of Borda there is a peak more than 11,000 feet in height. SNELLIUS.--A very fine ring-plain, 50 miles in diameter, S.E. of Petavius, with terraced walls, considerably broken on the S.E. by craters, &c. It rises on the E. nearly 7000 feet above a dark floor, which contains a central mountain. N.E. of Snellius is a smaller ring- plain (Snellius _a_), and due E. a curious rough plateau, bordered on the N. and S. by a number of small craters. STEVINUS.--A somewhat larger ring-plain, S. of Snellius, with a border rising on the S. to more than 11,000 feet above a dark interior, which includes a bright central mountain. REICHENBACH.--A very abnormally-shaped ring-plain, about 30 miles in diameter, with a rampart nearly 12,000 feet high. The border is broken on the W., S., and E. by craters and depressions, and on the N. is flanked by two overlapping ring-plains, _a_ and _b_. On the S.W. lies a magnificent serpentine valley, fully 100 miles in length and about 12 miles in breadth at the N. end, but gradually diminishing as it runs southwards, till it reaches a depression N. of Rheita, where it terminates: here is scarcely more than 4 miles wide.