SPENCER : THE AFFINITY OF DADOXYLON TO CORDAITES. 99 
trunks of trees are found standing more or less erect, in others they 
are flattened on the bedding of the stone ; but the smaller twigs, 
leaves and fruitstones often occur in great abundance, and mingled 
promiscuously in the stone or shale, as the case may be. In many 
cases the fossils are imbedded in a smudgy coal which is evidently 
the mineralized remains of either the bark or cortical layer. 
Besides the remains of Dadoxylon, the sandstones abound in 
beautiful specimens of other Carboniferous plants, such as Calamites, 
Lepidodendra and Sigillaria, ferns, &c, which plainly indicate that 
these coal plants were not solely confined to the low-lying swampy 
ground but overspread most of the Carboniferous lands, and this 
fact explains the rapidity with which they seized upon and overran 
the new lands as they uprose above the level of the sea, which must 
have been repeated again and again as often as there are beds of coals. 
The numerous leaves bearing stomata, cardiocarpons, and other 
fruits found in coal balls, and now referred to the cycads, seem 
to indicate that the plants which produced them must have lived on 
the spot, but we must not overlook the possibility that these Cycadean 
fragments may have been brought into the coal swamps, from con- 
tiguous high lands or other areas where they may have grown, by 
winds or floods. Cases of this character are recorded by Lyell and 
other authors as having occurred in the Oolite and Tertiary stratas. 
Sandstone casts, or even large stems, showing the structure of 
the wood, such as those of Craighleith and Wide Open, do not tell 
us the real character of the plant ; something more than this is 
required before its relationship can be determined. It is necessary 
that the character of the pith, if it has any, and the cortical layer 
should also be known before its place in the vegetable kingdom can 
be assigned. 
The next most important discovery, concerning this plant, was 
made by Prof. W. C. Williamson, of Owen's College, who obtained a 
small branch of Dadoxylon from Coalbrookdale, in a remarkably good 
state of preservation. At one end of the stem the pith was exposed 
and showing the transverse bars pertaining to Sternbergia. Thus the 
two fossils Sternbergia and Dadoxylon were found to belong to one 
plant, Sternbergia as its pith and Dadoxylon as its woody stem. The 
