DEVONIAN PLANTS. ^9 



Lower Eriau of Gaspé ; Silurian (Upper Ludlow) of England ; and Silurian 

 (Cape Bon Ami) of New Brunswick {Daiosun). 



2. — N. HiCKSii, Dn. 



Prototaxites Hicksii, Dn. 

 Nematophycus Hicksii, Eth. 



Cells of the medulla, 12-22 /( in diameter, and somewhat compact. Hyphal 

 filaments, 1 - 1.5 /' in diameter, ' forming a rather less prominent plexus than in 

 N. Log'ani, otherwise the same. 



Specimens occurring only in small fragments and the structure represented 

 wholly by siliceous casts, with occasionally adherent fragments of carbonaceous 

 matter. 



Denbighshire Grit (Silurian) of Wales (Hicks). 



3. — N. CRASSUM, Fen. 



Nematoxylon crassum, Dn. 

 Celluloxylon primœvum, Dn. 



Radial tracts none ; open tracts freqiient, small and of irregular form and size. 

 Cells of the medulla thick-walled, showing two layers, and rather uniform, 

 35 /(in- diam.eter. Cells of the hyphal structure variable, 2-10 /^ in diameter. 

 Highly crystalline forms often show a replacement of the normal cells by a pseudo- 

 cellular structure (Celluloxylon). 



Specimens found only in fragments. Middle Brian of Gaspé {Bell), Hamilton 

 Group (Middle Eriau) of New York (Clarke). 



4. — N. LAXUM, Fen. 



Concentric layers and radial openings, none. Cells of the medulla, 15 - 31 /' in 

 diameter, thick- walled, remote and branching into hyphal filaments, 3-9 /' in 

 diameter, which form a compact network constituting the greater part of the struc- 

 ture, which is thus rendered very loose and spongy. 



Lower Erian of Gaspé (Datcson). 



5. — N. TENUE, Pen. 



Nemaloxylon tenue, Dn. 



Concentric rings and radial tracts, none ; open tracts small, irregular and fre- 

 quent. Structur(> dense, and traversed at intervals by tubular openings 10- 14 ft in 

 diameter. 



Cells of the medulla, ihin-walled, ilosely approximated and 5 - 8 /( in diameter. 

 Cells of the hyphal strii(ti;re 1 /< + . Structure highly crystalline and friable. Stems 

 small and invested by a thickish layer of coal. 

 Lower Erian of Gaspé (Bell). 



' These measurements refer only to the siliceous cast.?, and are, therefore, not strictly comparable with those 



for other species. 



