On tJie so-called Land Plants from the Lower Silurian of Ohio. 337 



of specimens of sea-floated land plants, which we have found in the 

 Devonian limestones of Ohio, all assert their botanical affinities by 

 these characters. The remains of fucoids, on tiie contrary, consist 

 almost universally of mere casts of their external surface, carbonaceous 

 matter and internal structure having both entirely disappeared. 



The physical condition of the region about Cincinnati, during the 

 Lo\ver Silurian age, strengthens the conclusion that the specimens 

 under consideration are not the remains of land plants. As I have 

 shown elsewhere,* the Cincinnati arch was raised at the close of the 

 Lower Silurian age. Subsequent to that time it formed a group of 

 islands, which, during the Devonian age, were probably covered with 

 luxuriant terrestrial vegetation. But during the period when the 

 Cincinnati Group was deposited an open sea occupied all this part of 

 the Mississippi Valley. The shores of this sea were formed by the Blue 

 Ridge, the Adirondacks, the Canadian Highlands, and the Eozoic area, 

 on the south shore of Lake Superior, nowhere nearer than 500 miles 

 from the locality where these specimens were found. In these circum- 

 stances we must regard it as extremely improbable that specimens of 

 two species of land plants should be floated from this far-off* shore, and 

 should be deposited together in the calcareous sediment accumulating at 

 the sea bottom, near where Cincinnati now stands. That fucoids 

 should be found there is, however, not at all strange, for they float to 

 all parts of all oceans, and other fucoids are frequently met with in. 

 the Cincinnati Group of this vicinity. 



For the reasons given above, I should hesitate to rest upon these 

 specimens so important a conclusion as that promulgated by Mr.. 

 Lesquereux. I would not be understood, however, to assert positively 

 that they are not the remains of land plants, for they are too imperfect 

 to be decisive of that question, but only this, that they do not afford 

 characters which permit me to accept them as evidence of the existence 

 of land plants, and certainly not of Sigillarice in Ohio, during the 

 Lower Silurian age. 



The remains of what have been called land plants have been discovered 

 in the Lower Cambrian sandstones of Sweden, and two species of 

 these have been described (Eophyton Linneamim, Torell, and E. Toreli, 

 Linnarsson). The specimens are said by all geologists not to be the 

 remains of algae, but they are considered to be vascular cryptogams 

 or monocotyledons. It is not certain, however, that they are not 

 thallogens, as all traces of structure are lost, and nothing is left but 

 the impression of the external surface. 



=•■ Geological Survey of Ohio, vol. i, part i, page 93. 



[ In September, 1871, I read an essay before the Cincinnati Society of Natural History, to 

 show there was an island elevated in this locality, at the close of the Lower Silurian period, 

 which I called the island of Cincinnati. The same view, however, was entertained by several 

 geoloffist-s long before the Ohio survey had an existence.— Ed.] 



