RABBI LEVI.--A larger but less obvious formation than either of its neighbours, Zagut and Lindenau, abutting on the S. side of them. It is about 55 miles in diameter, and is enclosed by a border somewhat difficult to trace in its entirety, except under oblique light. There are some large craters within it, of which one on the N. side of the floor is especially prominent. NICOLAI.--A tolerably regular ring-plain, 18 miles in diameter, S. of Riccius, with a border, rising more than 6000 feet above a level floor, on the N. side of which Schmidt shows a minute crater. The bright plain surrounding this formation abounds in small craters; and on the W. is a number of curious enclosures, many of them overlapping. VLACQ.--A member of a magnificent group of closely associated formations situated on the greatly disturbed area between W. long. 30 deg. and 45 deg. and S. lat. 50 deg. and 60 deg. It is 57 miles in diameter, and is enclosed by terraced walls, rising on the W. about 8000 feet, and on the E. more than 10,000 feet above the floor. They are broken on the S. by a fine crater. In addition to a conspicuous central peak, there are several small craters, and low short ridges in the interior. HOMMEL.--Adjoins Vlacq on the S. It is a somewhat larger and a far more irregular formation. On every side except the W., where the border is unbroken, and descends with a gentle slope to the dark interior; ring- plains and smaller depressions encroach on its outline, perhaps the most remarkable being Hommel _a_ on the N., which has an especially brilliant wall, that includes a conspicuous central mountain, a large crater, and other details. The best phase for observing Hommel and its surroundings is when the W. wall is just within the evening terminator. PITISCUS.--The most regular of the Vlacq group. It is situated on the N.E. of Hommel (a curious oblong-shaped enclosure, Hommel _h_, with a very attenuated E. wall, and a large crater on a floor, standing at a higher level than that of Pitiscus, intervening). It is 52 miles in diameter, and is surrounded by an apparently continuous rampart, except on the E., where there is a crater, and on the S.W., where it abuts on Hommel _h_. Here there is a wide gap crossed by what has every appearance of being a "fault," resembling that in Phocylides on a smaller scale. There is a fine crater on the N. side of the interior connected with the S. wall by a bright ridge. Just beyond the E. border there is a shallow ring-plain of a very extraordinary shape. NEARCH.--A ring-plain, about 35 miles in diameter, on the S.W. of Hommel, forming part of the Vlacq group. TANNERUS.--A ring-plain, about 19 miles in diameter, between Mutus and Bacon. It has a central mountain. MUTUS.--A fine but foreshortened walled plain, 51 miles in diameter. There are two ring-plains of about equal size on the floor, one on the N., and the other on the S. side. The wall on the W. rises to nearly 14,000 feet above the interior.