In 1876 Williamson[194] described some petrified vegetative organs from the Lower Coal Measures of Lancashire under the name _Kaloxylon Hookeri_ characterised by a division of the secondary xylem into cuneate masses (fig. 415, C) like those in some recent Bignoniaceous stems. Williamson at first believed _Kaloxylon_ to be a stem, but in a later memoir he expressed the opinion that ‘it is difficult to believe that these organs have been other than roots’[195]. Felix[196] had meanwhile described a specimen from the Coal Measures of Westphalia as _Kaloxylon cf. Hookeri_ and suggested that it might be a waterplant. In 1894 Williamson and Scott[197] demonstrated that _Kaloxylon Hookeri_ is the root of _Lyginopteris_, a conclusion independently reached by Hick[198]. The roots of _Lyginopteris_ arise on all sides of the radially symmetrical stem in the pericycle region; they are copiously branched as is shown by the abundance of roots of various sizes in close association. No roots have been discovered exceeding 1 cm. in diameter nor have any been recorded with secondary periderm-tissue. The absence of root-hairs and the more or less lacunar structure of the cortex are indicative of swampy ground. It is seldom that the palaeobotanist has an opportunity of investigating the growing-points of Palaeozoic plants, and for this reason some well-preserved apices of _Lyginopteris_ roots, attributed to that genus on the ground of constant association with fragments of stems in the calcareous nodules of Dulesgate, are of special interest. One of these specimens was figured by Dr Stopes and Mr Watson[199] in their account of plant-bearing nodules, and a description of that and other examples has since been published by Prof. Weiss[200]. A longitudinal section of a root-tip, ·21 mm. in diameter at its broadest part, shows a root-cap which suggests an origin from a single cell, but an examination of the plerome-cylinder in a slightly tangential section does not afford conclusive evidence of the occurrence of a single initial cell. Weiss on the whole inclines to the view that _Lyginopteris_ possessed a single apical cell like the roots of Leptosporangiate Ferns, though he prefers to leave the decision open. Attention is drawn to the fact that the plate of tracheidal tissue in emerging lateral rootlets is vertical as in Phanerogams and not horizontal as in recent Pteridophyta.