Abstract
An enumeration of and key to North American (west of the Hundredth Meridian) species of Cephaloziellaceae are presented. A discussion of the distinguishing characteristics of each taxon and a distributional list with map is provided from the specimens examined. A total of 11 taxa (10 species and a variety) are reviewed here; of these Cephaloziella arctica is new to Colorado, C. elachista is new to Washington, C. divaricata is new to Nevada and Utah. C. divaricata var. scabra is new to Colorado and Texas, C. rubella and C. subdentata are new to California. [The other species are C. phyllacantha, C. brinkmanii, C. hampeana, C. stellulifera and C. turneri].