APPENDIX. 279 



2. Brian Flora. 



(1) Upper Ericm Sub-Flora : 



This corresponds to the Catskill and Chemung of the New York 

 series, and to the Upper Devonian ol Europe. 



The flora of this formation, which consists mostly of sandstones, 

 is not rich. Its most distinctive species on both sides of the Atlantic 

 seem to be the ferns of the genus Arehmopteris, along with species 

 referred to the genus Cyclopteris, but which, in so far as their barren 

 fronds are concerned, for the most part resemble Arehmopteris. 



The characteristic American species are Arehmopteris Jaclcsoni, 

 A. Rogersi, and A. ffaspiensis. Cyclopteris obtusa and C. (Platy- 

 phyllwm) Brownii are also very characteristic species. In Europe, 

 Arehmopteris Hibemica is a prevalent species. 



Leptophleum rhombicum and fragments of Psilophyton are also 

 found in the Upper Brian. There is evidence of the existence of 

 vast numbers of Rhizocarps in this period, in the deposits of spore- 

 cases {Sporcmgites Huronensis) in the shales of Kettle Point, Lake 

 Huron ; and in deposits of similar character in Ohio and elsewhere 

 in the West. 



The Upper Brian flora is thus very distinct from that of the 

 Lower Carboniferous, and the unconformable relation of the beds in 

 the Northeast may perhaps indicate a considerable lapse of time. 

 Still, even in localities where there appears to be a transition from 

 the Carboniferous into the Devonian, as in the Western States and 

 in Ireland, the characteristic flora of each formation may be distin- 

 guished, though, as already stated, there is apparently some mixture 

 in the South. 



(2) Middle JEricm Sub-Flora : 



Both in Canada and the United States that part of the great 

 Brian system which may be regarded as its middle division, the 

 Hamilton and Marcellus shales of New York, the Cordaites shales of 

 St. John, New Brunswick, and the middle shales and sandstones of 

 the Gaspe series, presents conditions more favourable to the abundant 

 growth of land-plants than either the upper or lower member. In 

 the St. John beds, in particular, there is a rich fern flora, comparable 

 with that of the coal-formation, and numerous stipes of ferns and 

 trunks of tree-ferns have been found in the Hamilton and Comifer- 

 ous series in the West, as well as trunks of Dadoxylon. It is, how- 

 ever, distinguished by a prevalence of small and delicate species, and 

 by such forms as Mymenophyllites and the smaller Sphenopterids> 

 and also by some peculiar ferns, as ArehcBopteris and Megalopteris. 



