476 AMERICAN SCIENTIFIC ASSOCIATION. 



SECTION OF GEOLOGY AND NATURAL HISTORY. 



ON THE VARIETIES AND MODE OP PRESERVATION OF THE FOSSILS KNOWN AS STERN- 

 BERGLffi — BY J. W. DAWSON, LL.D., PRINCIPAL OF M'GILL COLLEGE, MONTREAL. 



The fossils which have been named Sternbergiee and sometimes Artisiae, are 

 usually mere casts in clay or sand, having a transversely wrinkled surface, and 

 sometimes an external coaly coating and traces of internal coaly partitions. They 

 are found in the coal formation rocks of most countries, and very abundantly in 

 those of Nova Scotia. Until the recent discoveries of Corda and "Williamson, they 

 were objects of curious and varied conjecture to geologists and botanists, and 

 were supposed to indicate some very extraordinary and anomalous vegetable 

 structure. They are now known to be casts of the piths or internal medullary 

 cavities of trees, and the genera to which some of them belong have been pointed 

 out. In the present paper I propose to offer some further contributions toward 

 their history, and the geological inferences deducible from it. 



In a paper communicated to the Geological Society of London, in 1846, I stated 

 my belief that those specimens of Sternbergias which occur with only thin smooth 

 coatings of coal, belonged to rush-like endogens ; while those to which fragments 

 of fossil wood were attached, presented structures resembling those of conifers. 

 Additional specimens affording well-preserved coniferous tissue, in connection 

 with others in a less perfect state of preservation, have enabled me more fully to 

 comprehend the homologies of this curious structure, and the manner in which 

 specimens of it have been preserved independently of the wood. 



My most perfect specimen is one from the coal field of Pictou, cylindrical but 

 somewhat flattened. The diaphragms or transverse partitions appear to have been 

 continuous, though now somewhat broken. They are rather less than one-tenth 

 of an inch apart, and are more regular than is usual in these fossils. The outer 

 surface of the pith, except where covered by the remains of the wood, is marked 

 by strong wrinkles, corresponding to the diaphragms. The little transverse ridges 

 are in part coated with a smooth tissue similar to that of the diaphragms, and of 

 nearly the same thickness. In its general aspect, the specimen perfectly resembles 

 many of the or linary marked Sternbergite. 



On microscopic examination the partitions are found to consist of condensed 

 pith, which, from the compression of the cells, must have been of a firm bark-like 

 texture in the recent plant. The wood attached to the surface is distinctly conifer- 

 ous, with two and three rows of discs on the cell walls. It is not distinguishable 

 from that of Withain, or from the specimens figured by Professor Williamson. 

 The wood and transverse partitions are perfectly silicified, and of a dark brown 

 colour. The partitions are coated with small colourless crystals of quartz and 

 little iron pyrites, and the remaining spaces are filled with crystalline laminae of 

 sulphate of barytes. 



Unfortunately this fine specimen does not possess enough of its woody tissue to 

 show the dimensions or age of the trunk or branch which contained this enormous 

 pith. It proves, however, that the pith itself has not been merely dried and 

 cracked transversely by the elongation of the stem, as appears to be the case in 

 the Butternut, (Juglans Cinerea,) and some other modern trees; but that it has 

 been condensed into a firm epidermis-like coating and partitions, apparently less 

 destructible than the woody tissue which invested them. In this specimen the 



