THE EARLIEST PLANTS. 



791 



for which I now prefer the name Nematophyton. When in London, 

 in 1870, I obtained permission to exaraine certain specimens of spore- 

 cases or seeds from the Upper Ludlow (Sihirian) formation of Eng- 

 land, and which had been described by Sir Joseph Hooker under the 

 name PachytJieca. In the same slabs with these I found fragments of 



fossil wood identical with those of the Gaspe plant. Still later I rec- 

 ognized similar fragments associated also with Pachytheca in the Silu- 

 rian of Cape Bon Ami, New Brunswick. Lastly, Dr. Hicks has dis- 

 covered similar wood, and also similar fruits, in the Denbighshire grits, 

 at the base of the Silurian.* 



<.'».^. 





Fig. ^.—Nematophyton Logani (macrnified). Horizontal section, showing part of one of the radial 

 spaces, with tubes passing into it. 



They are trees of large size, with a coaly bark and large spreading 

 roots, having the surface of the stem smooth or irregularlj^ ribbed, but 

 with a nodose or jointed appearance. Internally, they show a tissue 

 of long, cylindrical tubes, traversed by a complex network of hori- 

 zontal tubes thinner walled and of smaller size. The tubes are ar- 



* "Journal of the Geological Society," August, 1881. 



