OF THE NEW RED SANDSTONE FORMATION OF PENNSYLVANIA. 
5 
of fi ne grained micaceous sandstone, which was taken from a quarry about fifty feet 
beneath the rock already described, I found beautiful imprints of hind and fore feet 
of an animal, which I have ventured to refer to the class Mammalia and order 
Marsupialia. The hind and the fore feet are obviously different. On the hind foot 
the toes are five, on the fore foot there are but four,” &c.* These discoveries were 
followed up by others, of “ foot-prints ” in the red sandstones of Schuylkill county, Pa., 
Formation No. 11 of Prof. Roger’s State Reports. In April, 1849, I observed in 
these red and grey rocks which underlie the conglomerate, (considered by Mr. Taylor, 
Mr. Hall, and other geologists, as the equivalent of the “ Old Red Sandstone ” of 
Europe,) a fine series of six pairs of foot-marks, which I referred to impressions made 
by a saurian, and which I named Sauropusprimcevus. (See Proceedings Am. Phil. 
Soc., 1849, and Trans., Vol. x., 1852.) 
Subsequently foot marks were found near Montreal by Mr. Logan, in the 
Potsdam sandstone, which he, Mr. Lyell and Prof. Owen, attribute to Chelonians , 
“ probably an estuary Emydian Tortoise.”f 
The very able memoir of Prof. Hitchcock, on the foot-prints of the New Red Sand¬ 
stone of the Valley of the Connecticut, read before the American Academy of Arts 
and Sciences, April, 1848, Volume Third, gives us a systematic account of forty- 
nine species of fossil foot-marks of the United States, with numerous exceed¬ 
ingly well executed illustrations. Of these, twelve were quadrupeds, two were 
annelids or molluscs, three of doubtful character, and the remaining thirty-two were 
bipeds, chiefly birds, some of which were of gigantic size. 
Heretofore there had been no well established fact of the bones of Saurians or 
* Proceedings of the Acad. Nat. Sci., vol. 2, p. 179, and Ahi. Journ. of Arts and Sciences, vol. 48, p. 348. 
The reference of this animal to the order Marsupialia is no doubt an error, as it seems to be more of a Batracliian, 
and Dr. King, in his subsequent communication to the American Journal of Arts and Sciences, says the difference 
in the number of toes on the hind and fore feet, seem to indicate an alliance with the Batrachians. Professor 
Hitchcock has, in fact, in his description of it, in the Memoirs of the American Academy of Arts and Sciences, 
vol. 3, p. 218, placed this species under Dr. King’s name as Tlienaropus heterodactylus ; and he says 
“ that it is possible that it might have been a Chelonian. More probably, however, it was a Batrachian,” in 
which latter opinion I should certainly concur. 
f It is only due to American science to say, that great doubt has existed in the minds of geologists here, as to 
these tracks being made by vertebrate animals. Several members of the Academy of Natural Sciences of this 
city, about four months since, tried some experiments with a living tortoise; and we all came to the conclusion 
that the foot-marks, as represented, of the so-called Chelonians, could not have been made by the locomotion of a 
tortoise. 
Within a few days I observe, by a report of the meeting of the Geological Society of London, March 24th, that 
Mr. Owen himself had come to the conclusion, that the impressions in the Potsdam sandstone rocks of 
Beauharnois, near Montreal, could not have been made by Chelonians. The “foot marks,” therefore, of the red 
sandstones near Pottsville, above mentioned, present the oldest known air-breathing animal in the Palaeozoic 
rocks of this continent, and the oldest on record, except the Chelonian foot-prints in the Old Red Sandstone of 
Morayshire, and the skeleton of a reptile supposed, by Dr. Mantell, to be Lacertian, and called by him Telerpelon, 
if they be really lower in the series. 
