And finally we have the mystery of IinnČ, a crater named after Karl von LinnČ (known in this country under the Latinized version of his name, Linnaeus) and situated in the Mare serenitatis. LinnČ shows up against the dark mare plain as a whitish spot, Iooking aIike through the whole lunar day, too low to cast a noticeable shadow. A few astronomers beginning in about 1890 claimed that, under exceptional seeing conditions and with a big instrument, a tiny hole could ba discerned in the center of the white spot. But Schmidt, in 1843, described LinnČ as a crater some 6 miles across, and an estimated 1200 feet deep. He and several other astronomers of his period used LinnČ as a Iandmark in the otherwise smooth. mare plain, a reference point for measurements. Nobody would use it now for this purpose, even thouph it stands alone on the mare plain, nor is Schmidt's description even remotely correct. But neither does there seem any chance for a mistake, since Linne does stand isolated and the position of the white spot of today agrees with the position given in 1843.