APPENDIX. 



277 



similar to those of the underlying beds, though with some species 

 which extend upward into the Millstone Grit. In Scotland the alga 

 named Spirophyton and Archceocalamites radiatus — which in Amer- 

 ica are Erian — appear in this formation. 



(5) The Lower Carboniferous Sub-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 follow- 

 ing: 



Dadoxylon (Palmoxylon) antiquius, Dn. — A species with large 

 medullary rays of three or more series of cells. 



Lepidodendron corrugatum, Dn. — A species closely allied to L. 

 Veltheimianum of Europe, and which is its American representative. 

 This is perhaps the most characteristic plant of the formation. It 

 is very abundant, and presents very protean appearances, in its old 

 stems, branches, twigs, and Knorria forms. It had well-character- 

 ised stigmaria roots, and constitutes the oldest erect forest known in 

 Nova Scotia. 



Lepidodendron tetragonum, Sternberg. 



L. obovatum, Sternb. 



L. aculeatum, Sternb. 



L. dichotomum, Sternb. 



The four species last mentioned are comparatively rare, and the 

 specimens are usually too imperfect to render their identification 

 certain, but Lepidodendra are especially characteristic trees of this 

 horizon. 



Cyclopteris (Aneimites) Acadica, Dn. — A very characteristic fern, 

 allied in the form of its fronds to C. tenui folia of Goeppert, to C. 

 nana of Eichwald, and to Adiantites antiquus of Stur. Its fructifi- 

 cation, however, is nearer to that of Aneimia than to that of Adi- 

 antum. 



Ferns of the genera Cardiopteris and Hymenophyllites also occur, 

 though rarely. 



Ptilophyton plumula, Dn. — This is the latest appearance of this 

 Erian genus, which also occurs in the Lower Carboniferous of Eu- 

 rope and of the United States. 



Cordaites borassifolia, Brongt. 



On the whole, this small flora is markedly distinct from that of 

 the Millstone Grit and true coal -formation, from which it is sepa- 

 rated by the great length of time required for the deposition of the 

 marine limestones and their associated beds, in which no land-plants 



