of the border of Stadius at sunrise, terminating at an obscure semi-ring-plain.  Between this and the pointed N. termination of the W. border there is a wide gap, open to the north for a space of about 30 miles, appearing, except under very oblique illumination, as smooth and as devoid of detail as the grey surface of the Mare Nectaris itself.  If, however, this interval is observed at sunrise or sunset, it is seen to be not quite so structureless as it appears under different conditions, for a number of mounds and large humpy swellings, with low hills and craterlets, extend across it, and occupy a position which we are justified in regarding as the site of a section of the rampart, which, from some cause or other, has been completely destroyed and overlaid with the material, whatever this may be, of the Mare Nectaris.  The floor of Fracastorius is, as regards the light streaks and other features upon it, only second in interest to those of Plato and Archimedes, and will repay systematic observation.  Between thirty and forty light spots and craters have been recorded on its surface, most of them, as in these formations, being situated either on or at the edges of the light streaks.  On the higher portion of the interior (near the centre) is a curious object consisting apparently of four light spots, arranged in a square, with a craterlet in the middle, all of which undergo (as I have pointed out elsewhere) notable changes of aspect under different phases.  There are at least two distinct clefts on the floor, one running from the W. wall towards the centre, and another on the S.E. side of the interior.  The last throws out two branches towards the S.W.

ROSSE.—­A fine bright deep crater in the Mare Nectaris, N. of the pointed termination of the W. wall of Fracastorius, with which it is connected by a bold curved ridge, with a crater upon it.  A ray from Tycho, striking along the E. wall of Fracastorius passes near this object.  A rill from near Bohnenberger terminates at this crater.

POLYBIUS.—­A ring-plain, about 17 miles in diameter, in the hilly region S.E. of Fracastorius.  The border is unbroken, except on the N., where it is interrupted by a group of depressions.  There is a long valley on the S.W., at the bottom of which Schmidt shows a crater-chain.

NEANDER.—­This ring-plain, 34 miles in diameter, a short distance W.S.W. of Piccolomini, has a somewhat deformed rampart, which, however, except on the N., where there is a narrow gap occupied by a small crater, is continuous.  It rises on the E. nearly 8000 feet above the floor, on which there is a central mountain about 2500 feet high.  Schmidt shows some minor hills, a large crater on the N.E. side, and three smaller craters in the interior.