IV. On the structure of Sigillaria scutellata, Brongn., and other Eusigillarian stems, in comparison with those of other palæozoic lycopods

Abstract

Among the fragments of plant remains, the structure of which is preserved, for us in the coal halls of the Lower Coal Measures of Lancashire and Yorkshire, Sigillarian stems have hitherto proved to be extremely infrequent. This fact has not escaped notice. Williamson, in 1872, remarked that “considering the abundance of Sigillariæ in the Coal-measures, it is marvellous that indisputable specimens displaying their internal organisation should he so rare; but such is the case.” Dr. Scott, in 1900, suggested that the rarity of such stems in the petrified state may be due to the infrequent occurrence of branching, “for, of course, it is in the case of small branches, rather than of great trunks, that petrifaction, such as to preserve the tissues, is most likely to have occurred. The recent reopening of a coal working at Shore-Littleborough, in Lancashire, rich in calcareous nodules containing plant petrifactions, a mine which is now, thanks to the liberality of Mr. W. H. Sutcliffe, F. G. S., being worked solely for the coal balls, has, however, resulted in the discovery of several well-preserved stems of ribbed Sigillarias of the Rhytidolepis type, which are described here. These specimens have been obtained by Mr. Lomax, one by one, as the result of a special search for this material, extending from July 1904 until the beginning of the present year (1907). Our thanks are due to him for the trouble he has taken to obtain the petrifactions, and for the skill with which he has prepared the sections.