界海
Virchow is a small lunar impact crater that is located on the northwestern interior floor of the prominent crater Neper. The latter formation lies near the eastern limb of the Moon, along the southern edge of the Mare Marginis. Observation of this area is hindered due to foreshortening, as well as libration effects. It was named after German physician Rudolf Virchow in 1979. Before, this crater had the designation Neper G.