Probably from the great preponderance of interest attaching to the Devonian rocks of North and South Devon the Culm Measure rocks, constituting the great central table land, have been to a certain extent overlooked. The attempt to subdivide them by ascertaining their different lithological characteristics, and observing to what extent these characteristics are peculiar to definite horizons, Las seldom been made. We may, infact, sum up the literature of the subject with one notable exception—the late Prof. J. Phillipsinhis “Figures and Descriptions of the Palasozoic Fossils of Cornwall, Devon, and W. Somerset”—as bearing upon the position.of the series as a whole, or calling attention to some special point of interest.