Page:Journal of botany, British and foreign, Volume 34 (1896).djvu/347

FOSSIL PLANTS OF THE COAL-MEASURES. 321 All these localities lie fairly close together, the most westerly being more than 1200 miles from Amboyna. A. oceanica lies very near A. scabra Benth. from British India, and is easily distinguished from other species of the section Hellenia with a nodding inflorescence, such as A. decurva Ridley. Baron von Hiigel's specimens lead one to suppose that the curvature of the inflorescence becomes more marked as it grows older, being very slight when the buds first begin to open. In cases where the flowers are much crowded the axis of the inflor- escence becomes twisted so as to obscure the ^ divergence which is present. Such might account for the want of it in Rumphius' figure. — I. H. Burkill, in Proc. Camhridye Phil. Soc. ix. 93. NOTICES OF BOOKS. Further Observations on the Orfjanization of the Fossil Plants of the Coal- Measures. By W. 0. Williamson. LL.D., F.R.S., and D. H. Scott, F.R.S. Part ii.— The Roots of Calamites. Part iii. — Lyginodendron and Heterangium. [Philosophical Transactions, clxxxvi B. pp. 683-779.] After completing nineteen memoirs dealing with the organi- zation of the fossil plants of the Coal-Measures, the late Professor Williamson was fortunate enough to obtain the co-operation of Dr. D. H. Scott in beginning a new series of communications to the Royal Society, extending and revising the work of the earlier con- tributions. In Part i. of the second series, an extremely full account was given of the stems and fructification of the well-known Car- boniferous genus Calamites ; the genus Sphenophyllum was also dealt with in detail, and its autonomous nature clearly demonstrated. In Part ii. our knowledge of the former genus is rendered still more complete. For many years we have been familiar with the existence of root-like appendages to the nodes of calamitean stems ; and comparatively recently, Prof. Renault of Paris proved the identity of the genera Astromyelom and Calamites, the former being simply the root of the latter. In the present memoir the histology of the Calamites root is described with great clearness and completeness, and the organic continuity of stem, roots, and rootlets satisfactorily established. The roots of Calamites differ from the stems in the absence of nodes, the usually solid pith, and the absence of canals accompanying the vascular bundles. At the periphery of the pith, which in the larger specimens is occupied by thin-walled paren- chymatous cells, there occur several groups of primary xylem, showing a distinct centripetal arrangement of the tracheids ; each group is triangular in form, with the spiral tracheids of the protoxylem occupying the apex. In a few exceptionally well- preserved sections, groups of primary phloem are seen alternating with the xylem. This typical root-arrangement of the primary xylem and phloem is beautifully shown in one of Mr. Brebner's