466 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 20, 



different aspects in different parts of the axis of the same rhizome. 

 This structure, it may be observed, corresponds perfectly with that 

 of the aerial stem of the same Plant, illustrated in my paper on the 

 Devonian Plants of Gaspe, the differences being merely those which 

 might have been anticipated from the greater size of the rhizome, 

 and its probably subaquatic or subterranean character. I have en- 

 deavoured, in PL XVIIL figs. 22 a to 22 g, to represent the structures 

 above described, which, with what was previously known, almost 

 complete our knowledge of this interesting Plant. 



It is further interesting to observe that Psilophyton princeps has 

 now been found to extend from the very bottom of the Devonian 

 series to its upper members, and throughout every part of Eastern 

 America in which land-plants have been found in these beds. That 

 it has not been recognized in Europe I attribute to its want of de- 

 cided external characters, when in an imperfect state of preservation, 

 having caused it to be mistaken for Algae, roots, &c. Similar views 

 might have prevailed here, but for the vast profusion of these Plants 

 found in situ in Gaspe, and the admirable preservation both of their 

 external markings and internal structure. 



2. Nematoxtlon crassum, gen. et spec. nov. PI. XIX. fig. 24. 



Fragments of wood with a smooth thin bark, and a tissue wholly com- 

 posed of elongated cylindrical cells with irregular pores or markings. 

 No pith, medullary rays, nor rings of growth. 



The specimens to which the above description refers are fragments, 

 the largest of which may have been 2 inches long, an inch wide, 

 and half an inch thick. They present under a magnifying-glass a 

 fibrous appearance (as if made up of thin threads or wires), from which 

 I have taken the name of the genus. They are calcified, and when 

 sliced show their structures very perfectly. Under the microscope 

 they at first sight remind the observer of the structure of Prototax- 

 ites ; but the cells are of one-third greater diameter than in P. Logani, 

 and are destitute of its peculiar markings, and there are no rings of 

 growth or medullary rays. The wood-cells are of great length, some- 

 what tortuous, loosely aggregated, and much thickened, by ligneous 

 deposit, which appears to be traversed by many narrow tortuous 

 lines or pores. The whole stem seems to be perfectly homogeneous, 

 and the only other structure observed was a faint and doubtful trace 

 of the existence of parenchymatous cells in some of the spaces be- 

 tween the fibres. The figures show a longitudinal and cross section, 

 magnified, and a few detached cells or woody fibres still more highly 

 magnified. 



With respect to the affinities of this tissue, I can give no opinion. 

 It may have been that of a Plant whose stem, destitute of true vessels 

 and composed of woody fibres imbedded singly in cellular tissue, bore 

 the same relation to that of an Endogen which Prototaodtes bears to 

 an ordinary Exogen. On the other hand, it has a sufficiently strong 

 resemblance to the fibrous outer bark of some Sigillaria? to render 

 it possible that it may have belonged to a Plant of this character, of 

 which the axis and inner bark have perished. 



