THE FLORA OF THE COAL FORMATION. 423 



"We shall commence our survey of the Coal flora with the higher 



forms of plant-life, which arc also those most akin to the plants of the 



present world. 



Class of Gymnosperms. 



1. Conifer ce or Phies. 



Four species of pines have heen recognised in the Coal formation of 

 Nova Scotia and New Brunswick. They arc known principally as 

 drift trunks imbedded in the sandstones, and these are so abundant as 

 to indicate that extensive pine forests existed, perhaps principally in 

 the uplands, higher than the Coal swamps. The trunks are also fre- 

 quently so well preserved, owing to the infiltration of carbonate of 

 lime or silica into their cells, that their most minute structures can be 

 observed as readily as in the case of recent wood. They may all be 

 included in the genus Dadoxylon, a name which means simply pine- 

 wood. The wood of these trees, however, more resembles that of the 

 Araucarian pines of the southern hemisphere than that of our ordinary 

 pines. 



One of the species, D. antiquiiis, is closely allied to D. Withami of 

 Great Britain, and, like that species, belongs to the Lower Carbon- 

 iferous Coal measures. Its structure is of that character for which 

 Brongniart proposed the generic name " Palwuxylon."* Another 

 species, D. Acadianum, is found abundantly at the Joggins and else- 

 where in the condition of drifted trunks imbedded in the sandstone of 

 the lower part of the Coal formation and the upper part of the Mill- 

 stone-grit series. The third species, D. materia rium, is very near to 

 D. Brandlingii of Great Britain, and may possibly be only a variety. 

 It is especially abundant in the sandstone of the Upper Coal formation, 

 in which vast numbers of drifted trunks of this species occur in some 

 places. The fourth species, D. annidatum, presents a very peculiar 

 structure, probably of generic value. It has alternate concentric rings 

 of discigcrous woody tissue, of the character of that of Dadoxylon, and 

 of compact structureless coal, which either represents layers of very 

 dense wood or, more likely, of corky cellular tissue. Iu the latter case, 

 the structure would have affinities with that of certain Gnetacea or 

 jointed pines, and of Cycads. 



Though coniferous trees usually occur as decorticated and prostrate 

 trunks, I have recorded the occurrence of one erect specimen, in a sand- 

 stone a little above the " Main Coal," at the Joggins. It probably 

 belonged to the species last named. Tissues of coniferous trees are 

 v.ry rare in the coal itself. Most of the tissues marked with discs on 

 the cells like those of pines, found in the coal, belong to Sigillaria and 



* Ancient wood. 



