In cultures from the pharynx, one frequently observed Gram‐positive, catalase positive cocci with characteristic transparent to grayish white colonies with a coherent consistency. These often adhered firmly to the agar surface. Eighteen such strains, including one from bronchial secretion and three from blood cultures, were subjected to detailed biochemical, serological and pathogenicity studies. They were also examined for lysostaphin sensitivity and the DNA base composition was determined. All the strains appeared as members of the same species. On the basis of a careful review of the literature, we found that this species had been namedStaphylococcus salivariusAndrewes&Gordon 1907 and was reisolated byGordon(19). However, the per cent (G + C) of these strains, their lysostaphin resistance and lack of anaerobic glycolysis are compatible only with the genusMicrococcus.The strains are not identical toGaffkya tetragena, Diplococcus crassus, Micrococcus hyicus, orM. freudenreichii.On the other hand, they possess all the properties ofM. mucilaginosusMigula 1900 which is therefore the earliest available epithet for this species and must be adopted. Micrococci have been reported to be typically novobiocin resistant. Neither the strains ofM. mucilaginosus, nor those ofM. freudenreichiiexamined by us adhered to this concept.M. mucilaginosusis important for its frequency of occurrence in cultures from the human pharynx, mostly without clear relation to disease. The possibility of potential pathogenicity in man cannot be decide