OlSr NEMATOPHYTON AND ALLIES. 45 



Cells of the medulla, 13 - 35 // iu diameter, interwoven, loosely aggregated 

 and turning into the radial spaces. Secondary structure composed of branching 

 iilaments 5 - 6 /< iu diameter, which branch from the cells of the medulla and 

 form a closely-woven intercellular plexus. 



Lower Erian of Graspé ; Silurian (Upper Ludlow) of England ; and Cape 

 Bon Ami, New Brunswick (Dawson). 



2. — N. LAXUM, Pen. — Concentric layers and radial openings, none. Cells of the medulla 

 15-31 /(in diameter, remote, and branching into secondary filaments 5.0-6.0 

 /A in diameter, which form a compact network, constituting at least half the 

 structure, which is thus rendered very loose and spougy. 

 Lower Erian of G-aspé ( Dawson) . 



3. — N. HiCKSll, Etii. — This species occvirs only in small fragments. 



Cells of the medulla, 12 - 22 /y iu diameter, ' and somewhat compact. 

 Secondary filaments, 1.0-1.5 /.i in diameter, forming a rather less j)i'ominent 

 plexus than in iV. Logani; otherwise the same. Associated with this species 

 there are frequently found clusters of spores measuring 1.58 /< in diameter. 



Denbighshire Grit (Silurian) of Wales (Hicks). 



2. — Laminated Fossils, ivith Nematophyton Logani. 



In December, 1887, Sir William Dawson submitted to me, for examination, a somewhat 

 peculiar fossil which he had found during the previous summer at Campbellton, New 

 Brunswick. It was imbt'ddcd in a somewhat coarse, grey sandstone, and associated with 

 numerous small fragments of vegetable matter. Externally, it presented the appearance 

 of a piece of laminated brown coal, which it really was. Its dimensions were 2.95 cm. 

 long by 1.35 cm. wide, and its thickness appears to be about the same as the width. 



The laminae, when separated, showed evident foldings. They were also found to lie 

 at all angles of obliquity with one another, while they also proved to have been pressed 

 into one another to such an extent that complete casts were frequent ; showing that they 

 must have been in a soft condition and subjected to considerable pressure while in that 

 state. The entire appearance continually suggested a mass of irregularly compacted, 

 half-rotten leaves. 



Under a pocket lens, there appeared no external evidence of veins, biit the surface 

 exhibited minute foldings, and also everywhere presented the appearance of a fine cellu- 

 lar structure. Several of the laminae were carefully separated from the mass and sub- 

 mitted to special treatment. Boiling with caustic potash for an hoiir or more produced 

 no sensible change in the character or in the clearness of the structure. Nitric acid ren- 

 dered the structure slightly clearer. On platinum foil the substance readily burned with 

 a copious flame, leaving behind a coherent film of grey ash. When mounted in balsam 

 and examined under the microscope, this failed to reveal any special structure, showing 

 that the silicification had not extended far enough to preserve the details of structure. 



' These measurements apply only to siliceous casts, and are, therefore, not strictly comparable with the 

 preceding. 



