PHOCYLIDES.--This extraordinary walled plain, with its neighbouring enclosures, is structurally very remarkable and suggestive. It consists of a large irregular formation, with a lofty wall, flanked on the N. by a smaller and still more irregular enclosure (_b_), the floor of which is 1500 feet above that of Phocylides, the line of partition being a high cliff, probably representing a "fault," whose shadow under a low sun is very striking. Phocylides is about 80 miles in maximum length, or, if we reckon the small enclosure _b_ to form a part of it, more than 120 miles. The loftiest peak, nearly 9000 feet, is on the W. border, near the partition wall. The continuity of the rampart is broken on the S. by a large crater. There is a bright ring-plain on the W. side of the floor, and a few small craters. Phocylides _b_ has only a solitary crater within it. Phocylides C, abutting on the W. flank of Phocylides, is about 26 miles in diameter. Its somewhat dusky interior is devoid of detail, but the outer slope of its W. wall is crowded with a number of minute craters, which, under good conditions, may be utilised as tests of the defining power of the telescope used. Phocylides A, on the bright S.W. plain, is a large deep crater with a fine crater-row flanking it on the W. WARGENTIN.--A most remarkable member of the Phocylides group, flanking the S.E. side of Schickard. Unlike the majority of lunar formations, its floor is raised considerably above the surrounding region, so that it resembles a shallow oval dish turned upside down. It is 54 miles in diameter, and, except on the S.W. (where it abuts on Phocylides _b_, and for some distance is bounded by its wall), it has only a border of very moderate dimensions. On the N.E. slope of this ghostly rampart I have seen a distinct little crater, and two much larger depressions on the N.W. slope. There are some low ridges on the floor, radiating from a nearly central point, which have been aptly compared to a bird's foot. SEGNER.--A fine ring-plain, 46 miles in diameter, on the S.E. side of Schiller, with a linear border on every side except the N. At a peak on the W., whose shadow is very remarkable, it rises to a height of more than 8000 feet above the outer surface. There is a crater on the S.W. wall, another on the N.W. wall, and several depressions on the outer slope on this side. The central mountain is small but conspicuous. A large unnamed enclosure extends N. of Segner: it is larger than Schiller, and is surrounded by a lofty barrier. The bright plain between this and the latter is worth examination under a low sun.