The fossil flora of the Culm Measures of North-west Devon, and the palæobotanical evidence with regard to the age of the beds.

The carboniferous rocks which occupy an area of 1200 square miles in Devon, Somerset, and Cornwall, are generally known as the Culm Measures, a name first applied to them by Sedgwick and Murchison in 1838; the word “culm” being an ancient Devonshire term for the impure coal, which is confined to one horizon in these beds in the neighbourhood of Bideford. Sedgwick and Murchison, in their classic memoir on the physical structure of Devonshire (1840), instituted a twofold division of these rocks, the Upper and the Lower Culm Measures, and this classification is maintained here. At the present time, our knowledge of the Lower Culm Measures is on an altogether different footing to any which we possess of the Upper division.