Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/359

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Count Sternberg has applied the name Syringodendron to many species of Sigillaria, from the parallel pipe-shaped flutings that extend from the top to the bottom of their trunks. These trunks are without joints, and many of them attain the size of forest trees. The flutings on their surface bear dot-like, or linear impressions, of various figures, marking the points at which the leaves were inserted into the stem. This fluted portion of the Sigillariæ, formed their external covering, separable like true bark from the soft internal axis, or pulpy trunk; it varied in thickness from an inch to one eighth of an inch, and is usually converted into pure coal. (See Pl. 56, Fig. 2. a, b, c.)

A fleshy trunk surrounded and strengthened only by such thin bark, must have been incapable of supporting large and heavy branches at its summit. It therefore probably terminated abruptly at the top, like many of the larger, species of living Cactus, and the abundant disposition of small leaves around the entire extent of the trunk seems to favour this hypothesis.

The impressions, or scars, which formed the articulations of leaves on the longitudinal flutings of the trunks of Sigillariæ, are disposed in vertical rows on the centre of each fluting from the top to the bottom of the trunk. Each of these scars marks the place from which a leaf has fallen oil, and exhibits usually two apertures, by which bundles of vessels passed through the bark to connect the leaves with the axis of the tree. No leaf has yet been found attached to any of these trunks; we are therefore left entirely to conjecture as to what their nature may have been. This non-occurrence of a single leaf upon any one of the many thousand trunks that have come under observation, leads us to infer that every leaf was separated from its articulation, and that many of them perhaps, like the fleshy interior of

in diameter. The lower end was broken off abruptly. Lindley and Hutton's Foss. Flora, vol. i. p. 153.