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.

MANZINUS.—­A walled plain, nearly 62 miles in diameter, with a terraced rampart rising to a height of more than 14,500 feet above the interior.  Schmidt shows three craterlets on the floor, but no traces of the small central peak which is said to stand thereon, but to be only visible in large telescopes.

SCHOMBERGER.—­A large walled-plain adjoining Simpelius on the S.W.  Too near the limb for satisfactory observation.

WEST LONGITUDE 20 deg.  TO 0 deg.

DELAMBRE.—­A conspicuous ring-plain, 32 miles in diameter, a little S. of the equator, in W. long. 17 deg. 30 min., with a massive polygonal border, terraced within, rising on the W. to the great height of 15,000 feet above the interior, but to little more than half this on the opposite side.  Its outline approximates to that of a pentagon with slightly curved sides.  A section on the S.E. exhibits an inflexion towards the centre.  The crest is everywhere continuous except on the N., where it is broken by a deep crater with a bright rim.  The north-easterly trend of the ridges and hillocks on the E. is especially noteworthy.  The central peak is not prominent, but close under it on the E. is a deep fissure, extending from near the centre, and dying out before it reaches the S. border.  At the foot of the N.E. glacis there are traces of a ring with low walls.

THEON, SEN.—­A brilliant little ring-plain, E.N.E. of Delambre, 11 miles in diameter, and of great depth, with a regular and perfectly unbroken wall.  North of it is a bright little crater.

THEON, JUN.—­A ring-plain similar in size and in other respects to the last, situated about 23 miles S. of it on a somewhat dusky surface.  Between the pair is a curious oblong-shaped mountain mass; and on the E. a long cliff (of no great altitude, but falling steeply on the E. side) extending S. towards Taylor a.  Just below the escarpment, I find a brilliant little pair of craterlets, of which Neison only shows one.