Named after Fiorino (or Florentino) Ameghino - Argentine paleontologist and anthropologist (1854-1911).
Ameghino is a lunar impact crater located to the north of the Sinus Successus, a bay in the northeast part of Mare Fecunditatis. This formation was designated Apollonius C before being given a name by the IAU, in honour of the argentine scientific and paleontologist Florentino Ameghino. Apollonius itself is located to the east-northeast. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.