278 GEOLOGICAL SUEVEY OF THE TERRITOEIES. 



compounds, and whose geological relation has never been satisfactorily 

 determined either by stratigraphy or by animal paleontology. Professor 

 Billing refers its lower part to the Oriskany saiudstone of New York, 

 without positive evidence, however; its middle part is doubtfully con- 

 sidered by Professor James Hall as representing the Hamilton group. 

 Takiug'into consideration the data supplied by fossil plants whose remains 

 have been found from the base to the top of this formation, Professor 

 Dawson finds that they represent a succession, by multiplication of spe- 

 cific or generic forms, of the whole devonian flora, as far as it is known, 

 till now, and that therefore this enormous accumulation of sandstone 

 has been in constant process of formation during a whole epoch, expos- 

 ing in its successive strata the gradual development of its vegetable 

 types. Its divisions are not as yet positively defined by the celebrated 

 professor of Montreal. But surely a more detailed study of the distri- 

 bution of the species of fossil plants of the Gaspe will enable the paleon- 

 tologist to fix, by the grouping of related forms of plants, the different 

 stages of the devonian land formation, and thus afford points of com- 

 parison for future researches. 



This we can do distinctly for the Carboniferous age, taking as its 

 beginning or its base the Old Eed Sandstone, represented in this country 

 bytheCatskill period. IntheUpper Chemung, wehave here, as in Canada 

 and in England, some few remains first representatives of a peculiar 

 group of ferns, whose characters have no relation tothoseof any species 

 of our time. Its species have been described by the authors under vari- 

 ous generic names. They are referred to Gyclopteris or Adiantiten by 

 some ; to NoeggeratMa or Sphenopteris by others ; to Archeopteris or Fale- 

 opteris in more recent works. This multiplication of generic names 

 does not refer to uncertainty of characters. Every paleontologist 

 knows these plants ; but their undefined analogy has forced different 

 points of view in regard to their relation, and therefore caused this 

 confused terminology. These ferns, from their rare presence in the De- 

 vonian, become so predominant in the red shale of the Catskill period 

 of this country, and of the Old Red Sandstone of Europe, that they are 

 considered as characterizing the formation by their remains. This fact 

 is acknowledged even by geologists who do not tnke any account of 

 vegetable paleontology. The more common species of this group of 

 ferns — Paleopteris hybernica, P. Eoemeri, P. Boscii, described first from 

 the Red Sandstone of England, are represented in the red shale, Nos. ix 

 andx of the Pennsylvania geological reports, (the Catskill,) below Potts- 

 ville, Mauch Chunk, and other places. Paleopteris Halliana and P. Jaclc- 

 soni are American species of the same tpye. In Europe two species, P. 

 Iieussii& P. unequilateralis, ascend to the Sub-Carboniferous limestone, 

 and here also, as will be remarked below, we have two species known 

 already in the next higher stage of the Carboniferous. Therefore the 

 predominance in the Catskill beds of a group of plants which is still rep- 

 resented by a number of species at a higher stage of the Carboniferous, 

 marks its place with the last geological division rather than with the 

 Devonian. These Paleopteris species, like those of Megalopteris men- 

 tioned in the following division, have often been considered as Devoni- 

 an types ; this, apparently, because the Old Red Sandstone has been often 

 and is still sometimes admitted as Devonian. All the European species 

 described are referred to the Old Red or to the Culm, or Sub-Carbon- 

 iferous ; those of Canada to the upper beds of Gasp6, a formation which, 

 as remarked already, is not yet limited in its divisions, and may repre- 

 sent the Catskill by its upper members. 



To this lower member of the Carboniferous are referable a number of 



