— Coal Strata of Pennsylvania. 29 
in Fayette county, near Connelsville, (Second Series, vol. i, p. 268, ) 
nineteen miles from Greensburg, and about thirty from: Derry. 
Dr. King and the Rev. Mr. Hackey have visited this place, 
and they inform me that on the surface of a hard ledge of sand- 
stone exposed there, some unquestioned Indian hieroglyphics 
with the representation of two human heads and of a serpent, 
are to be seen. These are accompanied with tracks of birds and 
of hoofed quadrupeds, and lastly of a footprint resembling ex- 
actly that of a dog or wolf, and identical with some of the most 
common tracks on the stone at Derry. 
I have now only to express my thanks to Dr. King for the 
assistance Which he gave me in prosecuting these inquiries, in 
which his sole desire was to arrive at the truth, and to correct any 
mistakes into which he might have fallen. He now agrees with 
me in regarding those imprints only as genuine and fossil, which 
occur in Unity township, five miles from Greensburg. They con- 
sist, as I before stated, of the tracks of a large reptilian quadru- 
_ ped, ina sandstone in the middle of the carboniferous series, a 
fact so full of novelty and interest, that when we reflect on its 
importance, all disappointment in the abandonment of the spuri- 
ous footprints is forgotten. In no formation have so many exca- 
vations affording facilities of paleontological researches in Europe 
and America been made, as in the carboniferous, No other group 
of strata has yielded such unequivocal evidence of the presence 
on the spot, of dry land, or of its existence in the immediate 
vicinity ; and yet here in Pennsylvania, for the first time we meet 
with evidence of the existence of air-breathing quadrupeds eapa- 
ble of roaming in those forests, where the Sigillaria, Lepidoden- 
_dron, Caulopteris, Calamites, Ferns, and other plants, flourished. 
Few geologists will now think it safe to assume, that no other 
species or agg or even acs of 0 pcre vertebrata existed at 
that period. 
on iclinnions it may be pkoper for me to state, that having 
Gsienesby examined, in company with Prof. Hitchcock, the isk. 
thichnites of the valley of the Connecticut river, I have by no 
means been led to doubt the genuineness of those imprints from 
what I saw at Derry. The fossil markings on the Connecticut 
