47S AMERICAN SCIENTIFIC ASSOCIATION. 



or none, of the investing wood. In the case of those which retain any portion of 

 the wood, sufficient to render probable their coniferous character, the surface- 

 markings are similar in character to those of my Pictou specimen, but often vary 

 greatly in their dimensions, some having fine transverse wrinkles, others having 

 these -wide and coarse. Of those specimens which retain no wood, but only a 

 thin coaly investment representing the outer pith, many cannot be distinguished 

 by their superficial markings from those that are known to be coniferous, and they 

 occasionally afford evidence that we must not attach too much importance to the 

 character of their markings. 



The state of preservation of the sternbergia casts in reference to the woody 

 matter which surrounded them, presents, in a geological point of view, many 

 interesting features. Frequently, only fragments of the wood remain, in such a 

 condition as to evidence an advanced state of decay ; -while the bark-like medul, 

 lary lining remains. In other specimens the coaly coating investing the cast- 

 sends forth fiat expansions on either side, as if the sternbergia had been the mid- 

 rib of a long thick leaf. This appearance, at one time very perplexing to me, I 

 suppose to result from the entire removal of the wood by decay, and the flattening 

 of the bark, so that a perfectly flattened specimen may be all that remains of a 

 coniferous branch nearly two inches in diameter. A still greater amount of decay 

 of woody tissue is evidenced by those sternbergia casts •which are thinly coated 

 with structureless coal. These must, in many cases, represent trunks and branches 

 which have lost their bark and wood by decay; while the tough, cork like, 

 chambered pith drifted away to be imbedded in a separate state. This might 

 readily Lapp en with the pith of Cecropia; and perhaps that of these coniferous 

 trees may have been more durable ; while the wood, like the sap wood of many 

 modern pines, may have been susceptible of rapid decay, and liable, when ex- 

 posed to alternate moisture and dryness, to break up into those rectangular blocks, 

 which are seen in the decaying trunks of modern conifers, and are so abundantly 

 scattered over the surfaces of coal and its associated beds in the form of mineral 

 charcoal. 



Some specimens of sternbergia appear to show that they have existed in the 

 interior of trunks of considerable size. The best instance of this that I have 

 found is one from the South Joggins, which appears to show the remains of a tree 

 a foot in diameter, now flattened and converted into coal, but retaining a distinct 

 cast of a wrinkled sternbergia pith. 



Are we to infer from these facts that the wood of the trees of the genus Dadoxy- 

 lon was necessarily of a lax and perishable texture ? Its structure, and the occur- 

 rence of the heart wood of huge trunks of similar character in a perfectly mineral- 

 ized condition, would lead to a different conclusion ; and I suspect that we should 

 rather regard the mode of occurrence of sternbergia as cautioning against the too 

 general inference from the state of preservation of trees of the coal formation, 

 that their tissues were very destructible, and that the beds of coal must consist of 

 such perishable materials. The coniferous character of the sternbergia?, in con- 

 nection with their state of preservation, seem to strengthen a conclusion at which 

 I have been arriving from microscopic and field examinations of the coal and 

 carbonaceous shales, that the thickest beds of coal, at least in Eastern America, 

 consist in great part of the flattened bark of coniferous, sigillaroid and lepidoden- 

 droid trees, the wood of which has perished by slow decay, or appears only in the 

 state of fragments and films of mineral charcoal. This is a view, however, on 



