On the Coal Measures in particular he became an acknowledged authority , and his Observations on the Structure of Fossil Plants found in the Carboniferous Strata ( 1868-1875 ) formed one of the monographs of the Palaeontographical Society .
He became an expert on the Coal Measures , and his Observations on the Structure of Fossil Plants found in the Carboniferous Strata ( 1868-1875 ) was one of the studies of the Palaeontographical Society .