Clamp connections at the cheilocystidia in Mycena are invariably correlated with their presence in other elements of hymenium and subhymenium. In some species of the genus clamped cheilocystidia occur in both the four- and two-spored forms; in others, the cheilocystidia are clampless in the two-spored form. Two of the sections examined are shown to comprise species with clamped and species with clampless cheilocystidia, suggesting that the presence of clamps at the cheilocystidia is a character of specific rather than sectional importance. Two examples are given to illustrate the value of clamps at cheilocystidia as a distinguishing character Mycena jacobi and M. niveipes, long regarded as being identical, are here considered to represent two separate species.