374 THE CANADIAN NATURALIST. [Vol. X. 



Lepidodendra. About fifty are Ferns and thirteen are Ccda- 

 mites, Asteropliyllites and SpJienoj^hylld. The great abundance 

 and number of species of Sigillarice, Lepidodendra and ferns are 

 characteristic of this sub-flora ; and among the ferns certain 

 species of JVeuropteris, Fecopteris, Alethopteris and SphenopteriSy 

 greatly preponderate. 



(3.) The Mill stone Grit Suh-Jiora : — 



In this formation the abundance of plants and the number of 

 species are greatly diminished. Trunks of Coniferous trees of 

 the species DadoxijJon Acadiamini, having wide wood-cells with 

 three or more series of discs and complex medullary rays, be- 

 come characteristic. Calamites undulatuin is abundant and 

 seems to replace G. SitcJcovii, though G. cannceforinis and G. 

 Gistii continue. SiglUarice become very rare, and the species of 

 Lepidodendron are few, and mostly those with large leaf-bases. 

 Lepidojloyos still continues and Gordaites abounds in some beds. 

 The ferns are greatly reduced, though a few characteristic Coal- 

 formation species occur, and the genus Gardiopteris appears. 

 Beds of coal are rare in this formation ; but where they occur 

 there is in connection with them a remarkable anticipation of 

 the Coal-formation flora, which would thus seem to have ex- 

 isted locally in the Millstone Grit period, but to have found itself 

 limited by generally unfavorable conditions. In America, as in 

 Europe, it is in the North that this earlier development of the 

 Coal Flora occurs, while in the South there is a lingering of the 

 older forms in the newer beds. 



(4.) The Lower Garhoniferous Suh-flora : — 



This group of plants is best seen in the Shales of the Horton 

 series, under the Lower Carboniferous marine limestones. It is 

 small and peculiar. The most characteristic species are the fol- 

 lowing : — 



Dadoxylon (^Falceoxyloii), antiquius, Dn. — A species with 



large medullary rays of three or more series of cells. 

 Lepidodendron corritgatimi, Dn. — A species closely al- 

 lied to L. Veltheimianum of Europe, and which is its 

 American representative. This is perhaps the most 

 characteristic plant of the formation, and presents 

 very protean appearances, in its old stems, branches, 

 twigs and Knorria forms. It had well characterized 

 stigmaria roots, and constitutes the oldest erect forest 

 known in Nova Scotia. 



