Section IV, 1888. [ 27 ] Trans. Eoy. Soc. Canada. 



III. — On Nematophyton and Allied Forms from the Devonian [Erian) of Gaspê and 

 Bay des Chaleurs. By D. P. Penhallow, B. Sc. ( With Introductory Notes, 

 by Sir "William Dawson, F.E.S.) 



(Presented May 25, 1888.) 



I. — Introductory Geological Note. {Sir W. Dawson.) 



1. — Historical Sketch. 



My first introduction to the fossil plants since known as Prototaxites and Nematophyton, 

 was in 1855. When in that year I came to Montreal, the late Sir W. E. Logan showed 

 me, in one of the cases in the Museum of the Geological Stirvey, several large masses of 

 black, silicified wood, which he had collected some years before in the Erian Sandstones 

 of Gaspé, but which had not been studied microscopically. I was much interested in 

 these lîlants, and in others since described by me as Psilophyton, more especially as they 

 were the oldest fossil plants, other than Algse, which I had seen ; being found, according 

 to Logan, in the Lower Sandstones corresponding in age to the Lower Devonian of Eng- 

 land. By Sir "William's permission, I had slices of the best preserved specimens made 

 by Weston, and found that the structures were in a very perfect state. 



I had noticed that the trunk collected by Logan, which must have been a foot in 

 diameter, had resisted the compression which had flattened the other plants in the same 

 beds ; that the stems split into concentric layers when broken, like exogenous wood, and 

 that they showed regularly arranged linear papillae on the surface corresponding to the 

 leaf-bundles of many fossil plants ; that they presented transverse swellings or nodes, and 

 cavities or knots, indicating the breaking off of small branches ; that they possessed a 

 coaly bark of remarkable thinness and density. All these appearances led me to infer, 

 from past experience of fossil plants, that I had to deal with a very resisting and durable 

 kind of wood. I was, therefore, not a little surprised when I found the structure to con- 

 sist of loose, cylindrical tubes, running lengthwise in a very tortuous manner, and traversed 

 by radiating horizontal spaces which I could only compare with the narrow and imperfect 

 medullary rays seen in some Sigillarise, and in the less perfectly organized types of Cyca- 

 daceous and coniferous trees. These spaces, however, showed no structure except loose 

 tubes, which seemed to have fallen into them, but have been ascertained by Prof. 

 Penhallow to have a structural significance. The rings of growth I found to consist of 

 alternate bands of larger and smaller tubes, but the difierence of these seemed insufficient 

 to account for the very decided concentric cleavage and weathering of the stems, which 

 was more marked than it usually is in Palseozoic Conifers. 



The mode of occurrence and state of preservation of the specimens seemed to make it 

 certain that they had belonged to land plants ; but my previous experience did not supply 

 me with any similar structures. After carefully examining a number of slices with such 



