38 PENHALLOW AND DAWSON 



meters occur. It is obyiovis that all iliese opeuiugs represent the same kind of tissue — 

 that is, as far as they are concerned, the structure is perfectly uniform and simple. "We 

 further observe that, while the majority are cut transversely, some are cut more or less 

 obliquely, showing that the direction of all of them is not truly at right angles to the 

 section. Thus they are separated from each other by spaces often as great as the width 

 of the opening, and sometimes much greater. It cannot belong to a Phceuogamous 

 plant." ' 



After pointing out a want of resemblance to the vascular structures of G-ymnosperms 

 and Angiosperms, Mr. Carruthers combats the idea that medullary rays are present, and 

 endeavors to show that the " doirble series of spiral fibres " in reality consists of an inter- 

 cellular system of filaments, which traverse the structure in all directions. Finally, after 

 directing attention to the peculiar structure and psevido-exogenous growth of, as well as 

 the great size sometimes attained by, certain Algœ, Mr. Carruthers definitely announces 

 his views with reference to the probable affinity of Prototaxites, by assigning it to a new 

 genus, Nematophjjcua. 



It is unnecessary to review the discussion more in detail, and for a full account we 

 must refer to the original articles cited ; but with these salient points of the question 

 before us, we are now prepared to see how far the present examination will serve to 

 support the views announced. A resume of w^hat follows has already been given by 

 Sir Wm. Daw^son,- but we now desire to give the full results of our examinations up to 

 the present time. 



External Chakacter.— Specimen No. 5, iu the Peter Eedpath Museum, exhibits 

 the best preserved structure of all the specimens brought under my notice. It is black, 

 and uniformly silicified throughout. The surface, which is marked by numerous rather 

 fine, longitudinal ridges, shows the remains of a coaly layer, which appears to bear the 

 relation of a cortical structure to the parts within. This layer is quite thin — hardly ex- 

 ceeding three mm. — and very friable, readily breaking up in all directions into irregular 

 fragments. At about its central portion, the specimen shows a node-like swelling, which 

 is traversed by a narrow furrow passing quite around the stem, thereby imparting an 

 apijearauce closely resembling the node of a grass, and conveying the impression that it 

 must represent the insertion of a broad-based, sheathing-leaf Further examination, how- 

 ever, fails to show any remnants of vascular or other structure to support such a view. 



Several very large specimens of more highly silicified trunks, wholly devoid of a 

 coaly layer, show these swellings to occur at irregular intervals. It also appears that 

 they rarely extend for more than a short distance in a transverse direction, and that they 

 are not formed at a constant angle with the axis of growth. The appearance in such 

 cases is well shown in a specimen figured by Sir Wm. Dawson in his original descrip- 

 tion of the fossil.* 



None of the descriptions so far given recognise a pith, and in all of the specimens 

 examined by us there is no evidence w^hatever to show that such a structure was ever 

 present. The polished end of No. 5 does, nevertheless, exhibit certain lines (Plate I, 

 fig. 2) which, from their radial direction and general disposition in the stem, bear a 



1 M. Mic. Jn'l, viii, 164. ^ Geological History of Plants, 42. 



' Geol. Surv. Can., Fossil Plants, 1871, plate ii, 19. 



