"The authors of Fossil Floras, however able or accomplished they may be, have often to found their genera and species, and to frame their restorations, when they attempt these, on very inadequate specimens. For, were they to pause in their labours until better ones turned up, they would find the longest life greatly too short for the completion of even a small portion of their task. Much of their work must be of necessity of a provisional character--so much so, that there are few possessors of good collections who do not find themselves in circumstances to furnish both addenda and errata to our most valuable works on Palæontology. And it is only by the free communication of these addenda and errata that geologists will be at length enabled adequately to conceive of the by-past creations, and of that gorgeous Flora of the Carboniferous age, which seems to have been by far the most luxuriant and wonderful which our emphatically ancient earth ever saw." [Illustration: Fig. 2.] [Sidenote: Fig. 2. Bark of _Araucaria imbricata_.] The bark of trees at the present day often exhibits different kinds of markings in its layers. This may be illustrated by a specimen of Araucaria imbricata, which was destroyed by frost in the Edinburgh Botanic Garden on 24th December 1861. The tree was 24½ feet high, with a circumference of four feet at the base of the stem, and had twenty whorls of branches. The external surface of the bark is represented in Fig. 2. There are seen scars formed in part by prolongations from the lower part of the leaves, which have been cut off close to their union with the stem. The base of each leaf remaining in the bark has the form of a narrow elongated ellipse, surrounded by cortical foliar prolongations. The markings on the bark, when viewed externally, have a somewhat oblique quadrilateral form. On removing the epiphlœum or outer bark, and examining its inner surface, we remark a difference in the appearance presented at the lower and upper part of the stem. In the lower portion the markings have an irregular elliptical form, with a deep depression, and fissures where the leaves are attached (Fig. 3). Higher up the epiphlœal markings assume rather more of a quadrilateral form, with the depressions less deep, and the fissures for the leaves giving off prolongations on either side. Farther up the markings are smaller in size, obliquely quadrilateral, and present circular clots along the boundary lines chiefly (Fig. 4). Higher still the quadrilateral form becomes more apparent, and the dots disappear (Fig. 5). The epiphlœum thus presents differences in its markings at different heights on the stem. [Illustration: Fig. 3.] [Illustration: Fig. 4.] [Illustration: Fig. 5.] [Sidenote: Figs. 3, 4, and 5. Markings on Araucaria bark.]