1868.] DAWSON — THE COAL FLORA. 363 



Brown, of Sydney. Imagine a tall cylindrical trunk spreading at 

 the base, and marked by perpendicular rounded ribs, giving it the 

 appearance of a clustered or fluted column. These ribs are 

 marked by rows of spots or pits left by fallen leaves, and toward 

 the base they disappear, and the bark becomes rough and uneven, 

 but still retains obscure indications of the leaf-scars, widened 

 transversely by the expansion of the stem. At the base the trunk 

 spreads into roots, but with a regular bifurcation quite un- 

 exampled in modern trees, and the thick cylindrical roots are 

 marked with round sunken pits or areoles, from which spread 

 long cylindrical rootlets. These roots are the so-called Stigmariee, 

 at one time regarded as independent plants, and, as the reader 

 may have already observed, remarkable for their constant 

 presence in the underclays of the coal-beds. Casting our eyes 

 upward, we find the pillar-like trunk, either quite simple or 

 spreading by regular bifurcation into a few thick branches, 

 covered with long narrow leaves looking like grass, or, more 

 exactly, like pine leaves greatly increased in size, or. more exactly 

 still, like the single leaflets of the leaves of Cycads. Near the 

 top, if the plant were in fruit, we might observe long catkins of 

 obscure flowers or strings of large nut-like seeds, borne in rings 

 or whirls encircling the stem. If we could apply the woodman's 

 axe to a Sigillaria, we should find it very different in structure 

 from that of our ordinary trees, but not unlike that of the 

 Cycads, or false sago-plants of the tropics. A lumber-man would 

 probably regard it as a tree nearly all bark, with only a slender 

 core of wood in the middle ; and, botanically, he would be very 

 near the truth. The outer rind or bark of the tree was very 

 hard. Within this was a very thick inner bark, partly composed 

 of a soft corky cellular tissue, and partly of long tough fibrous 

 cells like those of the bark of the cedar. This occupied the 

 greater part of the stem even in old trees four or five feet 

 in diameter. Within this we would find a comparatively small 

 cylinder of wood, not unlike pine in appearance, and even in its 

 microscopic structure ; and in the centre a large pith, often 

 divided, by the tension caused in the growth of the stem, into a 

 series of horizontal tables or partitions. Such a stem would have 

 been of little use for timber, and of comparatively small strength. 

 Still the central axis of wood gave it rigidity, the surrounding 

 fibres, like cordage, gave the axis support, and the outer shell of 

 hard bark must have contributed very materially to the strength 



