The leafy hepatic species found in Mexico show a wide variety of geographic relationships and affinities. Though monographic studies are very few, and more certainly are needed, this volume reports on what is currently known from the literature and examination of specimens. The first and only comprehensive study of the Hepaticae of Mexico remains that of C. M. Gottsche in 1863 (De Mexikanske Levermosser). Beginning about 1944, Dr. A. J. Sharp of the University of Tennessee initiated his study of the mosses of Mexico. He and his assistants collected hepatics along with the mosses on many trips during the next 40 years. The resultant compilation of species listed in this volume includes known distribution and habitat information.