10 Devonian Plants. 



The specimen is nine inches in diameter, and presents through- 

 out a series of rings of growth, rather more than one-tenth of an 

 inch in average thickness. Under the microscope, the cross- 

 section exibits cells perfectly circular in outline, not crowded, but 

 becoming much smaller at the margins of the rings of growth, 

 where some large irregular openings perhaps represent resin- 

 ducts. The medullary rays are marked by clear structureless 

 spaces. In the longitudinal section, parallel to the medullary 

 rays, the wood-cells are seen to be much elongated, and to 

 terminate in conical points ; and their sides are covered with the 

 remains of a double series of spiral fibres, among which are a few 

 scattered roundish spots, which perhaps indicate a single row of 

 discs*. The cells of the medullary rays have been entirely 

 disorganized ; but the space which represents them in a tangential 

 slice, shows that they must have consisted of several rows of cells. 

 (Figs. 4 a—c.) 



In my late visit to Gaspe, I was so fortunate as to find a second 

 tree of this species imbedded in the strata, though having its 

 structure in a less perfect state of preservation than the specimen 

 above described. It was in a prostrate position, the trunk lying 

 S. W. and N. E., in a thinly bedded, crumbling, pyritous sand- 

 stone. The trunk is silicified, one foot five inches in its greatest 

 diameter, and eleven inches in its least, the difi'erence being due 

 to compression ; a branch five inches in diameter sprang from its 

 side. On the external surface was a thin layer of crumbling coal, 

 probably representing the bark. No pith was perceptible ; but 

 there was a channel or depression along the upper surface, as if a 

 pith-cavity had existed and, when the wood became softened by 

 decay, had given way to pressure. The age of this tree, as in- 

 dicated by its rings of growth, would be about one hundred and 

 fifty years ; so that, though the tissue appears lax, it was not of 

 more rapid growth than in modern conifers. The growth-rings 

 also in the specimen previously described, as well as in this, are 

 well marked, indicating a decided difi'erence of temperature in 

 the seasons of the Devonian year. I cannot propose for this 

 monarch of the old Devonian forests of Gaspe a better or more 

 appropriate name than that of its discoverer, and shall therefore 

 name it Prototaxites Logani. 



* This disc-like structure was first pointed out to me by Mr. Poe, of 

 Montreal, a very zealous and successful microscopist. 



