Micrococus or Micrococcus: How To spell?

The word Micrococus is misspelled against Micrococcus, a noun meaning "A genus of Spherobacteria, in the form of very small globular or oval cells, forming, by transverse division, filaments, or chains of cells, or in some cases single organisms shaped like dumb-bells (Diplococcus), all without the power of motion. See Illust. of Ascoccus."