APPENDIX. 



275 



common and widely diffused Carboniferous species, some of which 

 have extended to the Permian period in Europe as well. From the 

 upper beds, characterised by these and a few other species, there is a 

 gradual passage downward into the productive coal-measures, and a 

 gradually increasing number of true coal-formation species. 



It is worthy of remark here that the association in the Permo- 

 Carboniferous of numerous trunks of Dadoxylon with the branches 

 of Walchia and with fruits of the character of Trigonocarpa, seems 

 to show that these were parts of one and the same plant. 



This formation represents the Upper Barren Measures of West 

 Virginia, which are well described by Fontaine and White,* and the 

 reasons which these authors adduce for considering the latter equiv- 

 alent to the European Permian will apply to the more northern and 

 eastern deposits as well, though these have afforded fewer species of 

 plants, and are apparently less fully developed. 



(2) Coal-formation Sub-Flora : 



The Middle or Productive Coal-formation, containing all the beds 

 of coal which are mined in Nova Scotia and Cape Breton, is the head- 

 quarters of the Carboniferous flora. From this formation I have 

 catalogued f one hundred and thirty-five species of plants ; but, as 

 several of these are founded on imperfect specimens, the number of 

 actual species may be estimated at one hundred and twenty. Of 

 these more than one half are species common to Europe and America. 

 No less than nineteen species are Sigillarim, and about the same 

 number are Lepidodendra. About fifty are ferns and thirteen are 

 Calamites, Asterophyllites, and Sphenophylla. The great abundance 

 and number of species of Sigillariai, Lepidodendra, and ferns are 

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

 of Neuropteris, Pecopteris, Alethopteris, and Sphenopteris greatly 

 preponderate. 



These beds are the equivalents of the Middle Coal-measures, or 

 Productive Coal-measures of Pennsylvania, Ohio, &c, and of the 

 coal-formation proper of various European countries. Very many 

 of the species are common to Nova Scotia and Pennsylvania ; but in 

 proceeding westward the number of identical species seems to di- 

 minish. 



* " Report on the Permian Flora of Western Virginia and South 

 Pennsylvania," 1880. 



f " Acadian Geology," and " Pteport on Flora of Lower Carbonifer- 

 ous," 1873. 



