276 GEOLOGICAL SURVEY OF THE TERRITORIES. 



past years, the researches in the vegetable paleontology of the Lignitic 

 have greatly added to what was known of its domain when the former 

 reports were published. 



To consider the first objection — that fossil plants are rarely found in. 

 the geological formations which are mostly marine; that the vegetable remains 

 are mostly undeterminable fragments of leaves ; that they have been as yet 

 scarcely studied ; and that the records of the fossil floras are mere blanks — 

 it will be necessary to open a while these so-called blank records of our 

 North American geological floras and look over them a little. 



We cannot boast, indeed, of a wide acquaintance with the fossil plants 

 of the Silurian, for the good reason that tbey have been rarely looked 

 for and studied. The formations of that epoch being mostly marine, 

 their flora is represented by fucoidal remains, or plants which, originally 

 of a soft texture, have generally been deformed and rendered undetermi- 

 nable by maceration and compression. Prof. James Hall has, however, 

 described some of those primitive vegetable forms, and his contribu- 

 tions to the vegetable paleontology of the Silurian have been acknowl- 

 edged and honorably recorded by European authors. Of the twenty 

 species of Silurian plants described by Goppert in his Flora of the For- 

 mations of Transition, sixteen are credited to the authorship of Hall. 



Besides the general instruction afforded by the representation of 

 those plants of primitive ages, we find in them already, though uncer- 

 tain theircharacters may be, an authority for the identification of Silurian 

 strata in far distant countries. It is the case, for example, with Die- 

 tionema flabelliforme, Hall, Eich., which identifies, by its abundant re- 

 mains, the Lower Silurian of Norway and of Bohemia, &c, the Lingula 

 flags of England, Ireland, and the strata of the same age, the Potsdam 

 epoch of the United States and Canada. 



As I have merely to consider the remains of land-plants, the whole 

 Silurian flora might be left out of notice as foreign to the subject. But 

 even land-plants have their history, at least the first lines of it, writ- 

 ten in those Silurian formations, considered till now as a succession of 

 marine deposits, as a time when our planet was surrounded by w 7 ater, 

 and when as yet there was no land exposed to view. Two years ago a 

 few stems or branches were found in beds of hard clay of the Cincinnati 

 group of the Silurian, near Lebanon, Ohio. They were, after examina- 

 tiou, considered as remains of land-plants, and as representing upon 

 their surface the impression of scars as a species of Sigillaria. This 

 opinion, which was then contradicted, is now fully confirmed by a new 

 and more careful examination, made by competent judges, who admit 

 that the remains in question can represent only land-plants. We could, 

 therefore, chronicle the presence of land covered with vegetation as far 

 down as the Middle Silurian, if we had positive evidence concerning the 

 origin of these remains in the locality indicated by their labels. It is, 

 indeed, supposable that those fragments may have been found some- 

 where else, and have been casually mixed with specimens of the Cin- 

 cinnati group, though the place of origin is positively known and vouched 

 for by the owner of the specimens. The presence of land-plants in as 

 low a member of the Silurian receives, however, a degree of probability 

 from the recent discovery of remains of two species of this kind in the 

 Lower Helderberg of Michigan. Here no doubt is left either in regard to 

 the character of the plants, which are clearly exposed, or to the locality 

 and its reference to the formation.* One of the species is a small 

 Psylophiton ; the other belongs to the genus Annularia, but is evidently 



* This discovery is due to Dr. Roeminger, State geologist of Michigan. 



