The closest analogy perhaps is with what we were speaking of a little while ago, a geological fault, that is to say, a line in the crust of the planet where the rocky strata have been broken across and one side has dropped to a lower level. “The crater pit in the _Mare Nubium_, east of the ‘Straight Wall,’ is named Birt, and its twin, 75 miles farther east, is Nicollet. Look now at the hooked nose of your ‘dark woman.’ The huge wart upon it is a crater plain named Lassell. Between the lower end of the ‘Straight Wall’ and Lassell, and over the bridge of the ‘nose,’ a wedge-shaped mountain runs out into the _mare_. This is called the Promontorium Ænarium, and must have formed a magnificent outlook if ever a real ocean flowed at the foot of its cliffs. The ring with a crater on its wall below Lassell is Davy. You will note some very somber regions scattered over this part of the _Mare Nubium_. One of them forms the ‘dark woman’s’ eye, and just over it, like an eyebrow, is a curving range of hillocks, including some little craters. On the ‘cheek’—I am still utilizing the ‘dark woman’ as a kind of signboard—at the base of the ‘chin,’ appears a partly double range of large ring plains. The greatest of these, at the bottom, is named Fra Mauro, and you will notice within it a curious speckling of small craters. Adjoining Fra Mauro on the south are two intersecting rings, Barry being the name of the western and Bonpland that of the eastern one. The partially submerged ring is nameless, as far as I know, while the upper or southern member of the group, with a broad valley shut in between broken mountain walls opening out of its northern side, is Guerike. There is only one other object, on the extreme lower right-hand corner of the picture, to which I will ask your attention. It is a singular range of mountains thrown into a great loop at its northern end, and known as the Riphæan Mountains.” “It seems to me,” said my friend, putting her elbow on the table, and leaning her head a little wearily on her hand, “that there is a great sameness in these lunar scenes—always crater rings with or without central mountains, always peaks and ridges and chasms and black shadows. Truly variety is lacking.”