Xm APPENDIX. 



Springs, for great developments of the Portage- and Hamilton 

 groups, if both exist here. 



The thickness of the Chemung group was formerly estimated 

 at about 1500 feet in New York; but from Col. Jewett's dis- 

 covery, that a considerable thickness of the strata forming the 

 Catskill Mountains, that had for a long time been referred to the 

 Old Red Sandstone, really belongs to the Chemung, we may 

 perhaps infer that 1500 feet is considerably below the maximum 

 thickness of the latter formation in New York. Prof Henry D. 

 Rogers estimated its greatest thickness in Pennsylvania at more 

 than 3000 feet. 



From all the facts observed, I had at one time supposed that 

 the plant bed at Lewis's tunnel holds a position in the upper 

 part of the Devonian ; but as Prof Rogers informs me that the 

 Old Red, if it exists there, is probably but little developed, the 

 position of these plants may be more properly within the inferior 

 part of the lower or subcarboniferous series. 



Fossil Botany not coming within the range of my own especial 

 department of investigation, my object in studying these plants 

 was, at first, merely to identify the species, which it was supposed 

 had probably been described. After making extensive compari- 

 sons, however, with the figures and descriptions in a large number 

 of publications, without finding any species agreeing with them, 

 I arrived at the conclusion that they are new, and decided to 

 name and describe them. The specimens, however, have been 

 submitted to Prof. Lesqaereux, and afterwards to Dr. Newberry, 

 as well as in part (with tracings of others), to Prof. J. W. Daw- 

 son, of Montreal, all of whom are well known to be high authori- 

 ties on fossil botany ; and these gentlemen concui*red in the 

 opinion that the species are new ; though they differed somewhat 

 in opinion respecting the generic affinities of the ferns, which 

 happen to be types standing, as it were, intermediate between 

 several of the established genera. This peculiarity of these 

 forms, and the fact that the most important generic character 

 (the nature of the fructification) can very rarely be seen in speci- 

 mens of these older types of fossil ferns, render their classifica- 

 tion difficult, and give origin to conflicting opinions, among the 

 most careful and conscientious observers, respecting the generic 

 names under which the species should be ranged. 



I take pleasure in acknowledging my obligations to Prof. 

 Dawson, Prof. Lesquereux, and Dr. Newberry, for the sugges- 

 tions alluded to above, respecting these plants. 



Lepidodendron scobiniforme, M. 



PI. I, fig. 1. 



Cicatrices of smaller branches moderately distinct, small, or 



about 0.14 inch in length, and 0.09 inch in breadth, subovate in 



form, or rounded above and tapering to a mucronate point below, 



(38) 



