while the smaller strand is on its way to a higher level before bending outwards through the secondary wood. Slightly beyond the middle of the secondary xylem there is an arc of narrower tracheids comparable with an incomplete annual ring. Although zones or arcs of narrow tracheids are not uncommon in the wood of _Lyginopteris_ there is no satisfactory evidence of regularly recurring seasonal changes. On the outer face of the secondary wood are a few leaf-trace strands pursuing a vertical course in the pericycle region; but the structure and behaviour of these bundles are more clearly illustrated in the stem reproduced in fig. 403. The tissue between the crushed phloem and pericycle and the outer cortex (fig. 402) consists of radially compressed parenchyma with scattered secretory cells separated from the more internal tissue by a narrow band of periderm formed by a phellogen in the outer part of the pericycle. A larger and better preserved stem, 3·7 cm. in diameter, is seen in fig. 403. In this stem the pith of parenchyma and scattered sclerenchymatous nests is larger in proportion to the stele than in Binney’s type-specimen. From the inner edge of the secondary xylem several primary xylem-strands project as rounded wedges or tangentially elongated groups where two traces are laterally united in the perimedullary zone. The cylinder of secondary wood is partially interrupted at _r_ by the bending outwards of the stele of an adventitious root cut across transversely as it bends down after emerging from the outer cortical region. In more or less close association with the outer surface of the secondary xylem are four pairs of leaf-trace bundles and one larger trace at _d_ containing two widely separated protoxylem strands and faced externally with an arc of secondary xylem: this is a leaf-trace which shows by the slight constriction on the outer edge of its primary xylem that it is beginning to divide into a pair of equal strands. A precisely similar strand is shown on a larger scale in fig. 404, D. The twin bundles seen at _b_, fig. 403, represent a divided leaf-trace at a slightly higher level than the partially severed trace at _d_, and the arcs of secondary xylem are narrower. The appearance of the double leaf-trace at a still higher level is shown at _c_: the two strands are farther apart and the secondary xylem has almost disappeared, while those at _e_, nearer their entrance into the leaf-stalk, consist exclusively of primary xylem and phloem. At _a_ the two strands of a leaf-trace, still nearer to the petiole, are inclined towards one another preparatory to reunion after reaching the leaf-stalk. A slender root is seen in transverse section at _r′_ immediately outside the two leaf-bundles. As Williamson and Scott[106] have pointed out, there are always five leaf-traces beyond the xylem cylinder of a _Lyginopteris_ stem as seen in transverse section, and these traces in the pericycle, separated