The Devonian tetracorals are divided into 16 families, of which 3 are new, and 18 subfamilies, of which 5 are new. The families and subfamilies are described, and lists of included genera are given. One hundred and twenty seven genera of which 9 are new, are described and placed under their respective families and subfamilies. The original figures of the genotype species of each genus are illustrated, plus any supplementary figures that clarify the internal structure of the species. In addition, figures of supplementary species are included when they help describe and limit the genus. Thirty-nine additional genera are placed in synonymy. Original figures of the genotype species of all genera considered synonymous are included.