ABSTRACT: The new agglutinated foraminiferal genus Olgia with the type species Olgia pacifica (Cushman) 1924 from the tropical Pacific and the new family Olgiidae fam. nov. are described based on an EMstudy of the inner and outer structure and the ultrastructure of the shell wall of the type species Clavulina pacifica Cushman 1924. The new genus differs from Clavulina in its wholly triangular shell, partially subdivided chambers, and presence of sutural pores together with the opened ends of the elongated angular extinctions of the chambers at the shell angles forming half closed chamberlets. The new family differs from the family Chrysalidinidae Neagu 1968 of the superfamily Chrysalinoidea by its complicated chamber interior, in the character of its aperture, and presence of the internal tooth plates interconnected from chamber to chamber.