[MATTHEW] FLORA OF THE LITTLE RIVER GROUP NO. II 79 



" The trunks of this species appear to have had a strong tendency 

 to split in decay along the medullary rays, and in consequence the cross- 

 section often presents a radiating structure of alternating black lines, 

 representing the wedges of wood, and white rays of calc spar. The heart 

 wood seems to have had its cell walls much thickened and in consequence 

 to have been more durable than that nearer the surface. They appear 

 to have been drift trees, and to have been much worn and abraded before 

 they were imbedded in sediment." 



This description of D. Ouangondianum is somewhat varied and am- 

 plified in the memoir Fossil Plants of the Devonian and Silurian forma- 

 tion, of Canada (page 13 etc.). "The specimens found at St. John in 

 the so-called ' Dadoxylon Sandstone ' are partially carbonized, and 

 partially silicified, calcified or pyritized. The carbonaceous matter is 

 anthracite, and in some places films of it have the lustre and appearance 

 of graphite. When the calcified portions are acted upon by a dilute acid, 

 the carbonaceous matter can be recovered in a pure state and capable of 

 showing the fibres and their pores under the microscope; but in this 

 condition the pores present a mere reticulation without any appearance 

 of proper discs. When portions containing pyrites are submitted to the 

 action of dilute hydrochloric acid the pyritized parts remain and can be 

 separated. These seen under the microscope as opaque objects often 

 show the most beautiful casta of the fibres, ex;hibiting the discs in great 

 perfection on their surfaces. As is often the case with other fossil woods, 

 imperfectly preserved specimens show a tendency to radiating crystal- 

 line structures which are often curiously complicated with the radiating 

 cracks following the medullary rays, and the concentric lines of growth. 

 Fig. 1 shows a specimen of this kind as seen in polished transverse sec- 

 tion [another figure has been substituted for Dawson's example.] 



" More recently the ojfficers of the Geological Survey [of Canada] 

 have collected at Lepreau, New Brunswick, additional specimens of this 

 species, differing somewhat in their state of preservation from those at 

 St. John. They are compressed and silicified, and show the more minute 

 structures of the woody fibres even more perfectly than the specimens 

 previously in my possession. They exhibit the peculiar oblique arrange- 

 ment of the pores which is also seen in some Carboniferous species, as 

 well as ill the wood of some Sigillariae, and in the modern world is ob- 

 served in Cycadacege and in Taxine conifers." 



" No specimens which can be certainly regarded as the foliage or 

 fruit of this species have been found. A specimen of a trunk collected 

 by Mr. Matthew is stated to have had a cast of a Sternbergia pith no less 

 than two and a half inches in diameter. Judging from the analogy of 

 recent plants, this great diameter of the pith would indicate that the 



