376 LL, Lesquereux on the Coal Formations of N. America, 
A. obscura Lsqx., A. serrula Lsqx., A. rugosa Lsqx., with Pecop- 
teris arborescens Brgt. (abounding), P. notata Lsqx., P. distans 
Lsqx., P. oreopteridius Brgt., P. pusilla Lsqx., P. dubsa Lsqx., 
(referable with doubt to P. arborescens Brgt.,) P. cyathea Brgt., 
uta Bret., P. concinna Lsqx., P. incompleta Lsqx., mostly 
species peculiar to this coal. Pecopteris polymorpha Brgt. is also 
found in its shales. 
The genus Calamites is here represented by Calamites cruciatus 
Bret, C. dubius Bret. C. bistriatus Lsqx., C. disjunctus Lsqx. 
These two last species have been found only with this coal; but 
each has been established on single specimens and thus they 
are still uncertain. 
From this enumeration, it is evident that we have passed at 
this geological horizon to a vegetation much reduced in the size 
of its representatives and of a quite different character. The 
arborescent species belong to the ferns, or to Stgillaria, of small 
size. 
Our 4th coal is covered, as was said before, by a thick stratum 
of sandstone, generally conglomerate in part, varying in thick- 
ness from 10 to 150 feet. The vegetable fossil remains of this 
sandstone afford a new evidence of the predominance of the 
ferns at this geological horizon, and of the disappearance of 
Lepidodendron. It is the immediate deposit of silicified trunks 
of Psaronius, extending from Ohio to Virginia along the Great 
Kanawha river. At Shade river, near Athens, Ohio, the broken 
pieces of these trees are so numerous that they cover in places 
the bed of the creek.* They appear generally as pieces of small 
stems horizontally broken, varying from two to eleven inches 
in thickness. The largest specimen which I was able to find is 
apparently the base of a tree. It is nearly round, eleven inches 
in diameter, and perforated, not in its central part, but somewhat 
on one side, a regular round hole four inches in diameter. 
Mahoning sandstone and the great Pittsburg coal, have geod 
afforded hitherto very abundant materials for the study ‘ 
their botanical remains. It has been seen already that, in Penn- 
sylvania, this space is occupied by strata of shales, ener 
and limestone which are generally barren of coal, at least © 
_* Unhappily, I have not as yet been able to obtain for microscopical exam 9 
tion polished lamelle of sections of the collected species and cannot give @ 
account of them. But the work of preparing the specimens is now 10 ibe 
and the view of internal structure of those interesting remains will soon affor 
possibility of determining the species. 
