20 «L. Lesquereux on the Coal Formations of the United States. 
vegetable. As it is extremely rare to find in our coal measures 
a whole tree preserved by petrification, the study of a single 
species of the great vegetables of the coal ought to be pursued 
at the same place on a great number of specimens. This is al- 
ways a difficult task. But if we consider that before we are able 
to become well acquainted with any species of fossil plant, and 
especiaily to get a view of its stratigraphical and geographical 
distribution, we have to examine it closely at a great number o 
distant exposures, the difficulties of this study appear far greater. 
The collecting of specimens and their study would be greatly: 
encouraged by some good work with descriptions and figures o 
American fossil plants. Indeed, I have been repeatedly asked 
what were the books from which we could get that prelimin- 
ary acquaintance of fossil plants which is necessary to direct 
such researches. Hitherto nothing has been done in that line 
in the United States; at least nothing that can be easily ob- 
tained by the student, because all that has been published on 
the botanical paleontology of the coal is disseminated in scien- 
tific Journals or State Geological Reports that are not generally 
accessible. 
Before the publication of the Geological report of the State of 
Pennsylvania, a few species of our fossil plants had been described 
y Mr. Brongniart in his Fossil F'lora* from specimens sent to 
him, chiefly by Prof. Silliman, from Wilkesbarre and Zanesville. 
After this, Mr. Bunbury of England published in the Quarterly 
Journal of the Geological Society of London (vol. ii, p. 82) some 
remarks on species of fossil plants collected by Mr. Lyell at Frost- 
burg, Maryland. Very few of these species are described or even 
determined, for except Newropteris cordata, Pecopteris arborescens, 
Lepidodendron tetragonum, Lepidodendron aculeatum, Stigmaria 
ficcides, Asterophyllites and Calamites nodosus, all the species men- 
tioned in Mr. Bunbury’s paper are marked with signs of doubt. 
The general remarks of this celebrated English author are ve 
interesting indeed, but are useless for one beginning the study of 
the fossil plants of our coal measures. Even the three new spe- 
cies which he has described and figured are uncertain, being made 
from incomplete specimens. Inthe third volume of the same Jour- 
nal, Mr. Bunbury, examining some fossil plants from the Nova 
Scotia coal measures, sent to him by Mr. Richard Brown, men- 
tions, mostly without descriptions, and with a?, forty-eight species, 
of which seven are described and figured. The same remark as 
above can be applied to these species, except for Lepidodendron 
tumidum and Neuropteris rarinervis, ee a described and 
figured, though still from imperfect specimens. This Journal, vol. 
iil, No. 1, contains a Notice of vegetable impressions by Granger, 
* Histoire des Vegetaux Fossiles, 
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