E. of Gassendi) crosses the floor of d, and, I believe, partially cuts into its W. wall.  Another, the coarsest, abuts on a mountain arm connecting d with Mersenius, and, reappearing on the E. side, runs up to the N.W. wall of the other ring-plain, a, and, again reappearing on the E. of this, strikes across the rugged ground between a and Cavendish d, traversing its floor and border, as does also another cleft to the N. of it.  Cavendish d includes a coarse cleft on its floor, running from N. to S., which I have frequently glimpsed with a 4 inch achromatic.  There are two other delicate clefts running from the Gassendi region to the S.W. side of Mersenius, which are in part crater-rills.

CAVENDISH.—­A notable ring-plain, 32 miles in diameter, S.E. of Mersenius, with a prominently terraced border, rising at one point on the S. to a height of 6000 feet above the interior, on which are a few low ridges.  A large bright ring-plain (e), about 12 miles in diameter, breaks the continuity of the S.E. wall, and adjoining this, but beyond the limits of the formation, is another smaller ring with a central hill.  There is also a bright crater on the N.W. border.  The W. glacis is very broad, and includes two large shallow depressions.  An especially fine valley runs up to the N. wall, to the W. side of e.

VIETA.—­One of the finest objects in the third quadrant; a ring-plain 51 miles in diameter, with broad lofty walls, a peak on the west rising to nearly 11,000 feet, and another N. of it to considerably more than 14,000 feet above the interior.  It is bounded by a linear border, approximating very closely to an hexagonal shape, which is broken by many gaps and cross-valleys.  On the S., the S.W. and S.E. sections of the wall do not meet, being separated by a wide valley flanked on the W. by a fine crater, which has broken down the rampart at this place.  The N. border is likewise intersected by valleys and by a crater-row.  The inner slopes are conspicuously terraced.  There is a very inconspicuous central mountain and several large craters on the floor, some of them double.  Ten have been counted on the N. half of the interior.  On the S.E. of Vieta are two fine overlapping ring-plains, with a crater on the wall common to both.

DE VICO.—­A conspicuous little ring-plain, about 9 miles in diameter, with a lofty border, some distance E. of Mersenius.

LEE.—­An incomplete walled-plain, about 28 miles in diameter, on the S. side of the Mare Humorum, E. of Vitello, from which it is separated by another partial enclosure, with a striking valley, not shown in the published maps, running round its W. side.  If viewed when its E. wall is on the morning terminator, some isolated relics of the wrecked N.W. wall of Lee are prominent, in the shape of a number of attenuated bright elevations separated by gaps.  Within are three or four conspicuous hills.