VI. On the structure of certain limestone nodules enclosed in seams of bituminous coal, with a description of some trigonocarpons contained in them

The specimens of plants which we are about to describe were found imbedded in nodules of limestone, enclosed in a thin seam of bituminous coal not above 6 inches thick, in the lower part of the Lancashire coal-field. Their relative position is best understood from the following section (in a descending order). 1. Black shales containing Avicula papyracea, Goniatites Listen, Orthoceras attenuatum and other Mollusca, apparently of marine origin. 2. Bituminous coal enclosing a horizontal layer of limestone nodules containing fossil vegetable remains. 3. Fire-clay full of Stigmaria ficoides. The roof of the seam is also full of fossil shells, and those in the shales lie in immediate contact with the bituminous coal.