许癸努斯
Hyginus is a lunar caldera located at the east end of the Sinus Medii. It was named after ancient Roman astronomer Gaius Julius Hyginus. Its rim is split by a 220 kilometer-long rille, Rima Hyginus, that branches to the northwest and to the east-southeast. The crater is deeper than the rille, and lies at intersection of the rille's branches. Together, the crater and the rille form a prominent feature in an otherwise flat surface. Smaller craters along the length of the rille may have been caused by the collapse of an underlying structure.