Twenty-two fetal and two calf strains of spirilla have been studied chiefly with regard to the problem of identity. Twenty-one fetal strains are probably specifically the same. One fetal strain differs slightly from these, but in its agglutination affinities it belongs to the same group. Of two strains isolated from calves one has definite agglutination relations with the fetal strains, the other none. In the morphological and biological characters so far investigated all the strains agree closely with one another.