SU J. W. Dawson— Brian Flora of the United States. 



radiating ) Lit.- of ^ealariform vessels. In the cross section, 

 the axis consists of vertic;i 1 Inn wavy radiating bands of pseu- 

 doscalariform tissue, with intervening cellular matter. Enclos- 

 ing the axis is a cylinder of thin-walled cellular tissue traversed 

 by a few bundles of fibers. The outer surface has a dense 

 cortical structure, but unfortunately shows no external mark- 

 ings. This discovery affords another interesting link of con- 

 nection between the Erian flora of Eastern America and that 



We know from the rocks and fossils of Gaspe and St. John, 

 that in the Middle Devonian period there was much land on 

 the eastern side of the North American Continent. Bat at this 

 period the regions of western New York and Ohio and of 

 western Canada, were covered by the sea. It thus happens 

 that the land flora of the Hamilton and associated rocks of the 

 interior portion of the Continent, consists merely of di 

 mar, mt.'d ivmains carried out to sea. The number and variety 

 of these remains, however, testify in a remarkable manner to 

 the richness of the flora, representing as they do, though in an 

 imperfect manner, many species of Conifers, Tree-ferns, and 

 Arborescent Lycopods, all of which probably grew on limited 

 insular areas. 



To Professor Clarke we are also indebted for the discovery 

 of a remarkable tree of the Hamilton period (Celluhxyhn pri- 

 mcevum Dn.) : and Mr. P. M. Wright of Perm Yan, N. Y., has 

 recently added to the plants of the Portage and Chemung the 

 singular types of tree-fern, AMero^ieris Socdmrucensis Dn., an 

 equisetaceou- ] * >"t / >' 11/ c ' < </ I> , ] ' 

 affine, a plant allied to the well-kj m\ t Q/c ■ <li : /, ■« of the Irish 

 Devonian. These species have been described in the Journal 

 of the London Geological Society for May, 1881. 



IV. PSILOPHTTON AND PvHODEA. 



Keference is made to the abundant occurrence of the species 

 P.prtuceps and P. robusiins in the Lower Krian near Campbell- 

 ton, and the corroboration which the specimens afford of the 



of these plants so characteristic of the Erian both in Europe 



As it has, however, been suggested by some botanists that 

 />*■' ,.'i. :i hj,i may have been allied to the" ferns of Star's genus 

 Bhodea, I may state here that after the study of hoi 



. in every state of preservation, I have found no 

 trace of any fronds on the branches, but on the barren branches 

 minute acicular leaves, while the spore-cases, though in the 

 form of sacks, having some resemblance to those of Archceopte- 



